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Merge tag 'v3.5-rc6' into irqdomain/next

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Linux 3.5-rc6
This commit is contained in:
Grant Likely
2012-07-11 16:08:35 +01:00
parent 22076c7712 bd0a521e88
commit 80c1834fc8
995 changed files with 9755 additions and 5092 deletions
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13
kernel/cgroup.c
View File

@@ -255,12 +255,17 @@ int cgroup_lock_is_held(void)
EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
static int css_unbias_refcnt(int refcnt)
{
return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS;
}
/* the current nr of refs, always >= 0 whether @css is deactivated or not */
static int css_refcnt(struct cgroup_subsys_state *css)
{
int v = atomic_read(&css->refcnt);
return v >= 0 ? v : v - CSS_DEACT_BIAS;
return css_unbias_refcnt(v);
}
/* convenient tests for these bits */
@@ -4982,10 +4987,12 @@ EXPORT_SYMBOL_GPL(__css_tryget);
void __css_put(struct cgroup_subsys_state *css)
{
struct cgroup *cgrp = css->cgroup;
int v;
rcu_read_lock();
atomic_dec(&css->refcnt);
switch (css_refcnt(css)) {
v = css_unbias_refcnt(atomic_dec_return(&css->refcnt));
switch (v) {
case 1:
if (notify_on_release(cgrp)) {
set_bit(CGRP_RELEASABLE, &cgrp->flags);

10
kernel/events/core.c
View File

@@ -253,9 +253,9 @@ perf_cgroup_match(struct perf_event *event)
return !event->cgrp || event->cgrp == cpuctx->cgrp;
}
static inline void perf_get_cgroup(struct perf_event *event)
static inline bool perf_tryget_cgroup(struct perf_event *event)
{
css_get(&event->cgrp->css);
return css_tryget(&event->cgrp->css);
}
static inline void perf_put_cgroup(struct perf_event *event)
@@ -484,7 +484,11 @@ static inline int perf_cgroup_connect(int fd, struct perf_event *event,
event->cgrp = cgrp;
/* must be done before we fput() the file */
perf_get_cgroup(event);
if (!perf_tryget_cgroup(event)) {
event->cgrp = NULL;
ret = -ENOENT;
goto out;
}
/*
* all events in a group must monitor

19
kernel/exit.c
View File

@@ -72,6 +72,18 @@ static void __unhash_process(struct task_struct *p, bool group_dead)
list_del_rcu(&p->tasks);
list_del_init(&p->sibling);
__this_cpu_dec(process_counts);
/*
* If we are the last child process in a pid namespace to be
* reaped, notify the reaper sleeping zap_pid_ns_processes().
*/
if (IS_ENABLED(CONFIG_PID_NS)) {
struct task_struct *parent = p->real_parent;
if ((task_active_pid_ns(parent)->child_reaper == parent) &&
list_empty(&parent->children) &&
(parent->flags & PF_EXITING))
wake_up_process(parent);
}
}
list_del_rcu(&p->thread_group);
}
@@ -643,6 +655,7 @@ static void exit_mm(struct task_struct * tsk)
mm_release(tsk, mm);
if (!mm)
return;
sync_mm_rss(mm);
/*
* Serialize with any possible pending coredump.
* We must hold mmap_sem around checking core_state
@@ -719,12 +732,6 @@ static struct task_struct *find_new_reaper(struct task_struct *father)
zap_pid_ns_processes(pid_ns);
write_lock_irq(&tasklist_lock);
/*
* We can not clear ->child_reaper or leave it alone.
* There may by stealth EXIT_DEAD tasks on ->children,
* forget_original_parent() must move them somewhere.
*/
pid_ns->child_reaper = init_pid_ns.child_reaper;
} else if (father->signal->has_child_subreaper) {
struct task_struct *reaper;

6
kernel/panic.c
View File

@@ -27,7 +27,7 @@
#define PANIC_TIMER_STEP 100
#define PANIC_BLINK_SPD 18
int panic_on_oops;
int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
static unsigned long tainted_mask;
static int pause_on_oops;
static int pause_on_oops_flag;
@@ -108,8 +108,6 @@ void panic(const char *fmt, ...)
*/
crash_kexec(NULL);
kmsg_dump(KMSG_DUMP_PANIC);
/*
* Note smp_send_stop is the usual smp shutdown function, which
* unfortunately means it may not be hardened to work in a panic
@@ -117,6 +115,8 @@ void panic(const char *fmt, ...)
*/
smp_send_stop();
kmsg_dump(KMSG_DUMP_PANIC);
atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
bust_spinlocks(0);

20
kernel/pid_namespace.c
View File

@@ -184,11 +184,31 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
}
read_unlock(&tasklist_lock);
/* Firstly reap the EXIT_ZOMBIE children we may have. */
do {
clear_thread_flag(TIF_SIGPENDING);
rc = sys_wait4(-1, NULL, __WALL, NULL);
} while (rc != -ECHILD);
/*
* sys_wait4() above can't reap the TASK_DEAD children.
* Make sure they all go away, see __unhash_process().
*/
for (;;) {
bool need_wait = false;
read_lock(&tasklist_lock);
if (!list_empty(&current->children)) {
__set_current_state(TASK_UNINTERRUPTIBLE);
need_wait = true;
}
read_unlock(&tasklist_lock);
if (!need_wait)
break;
schedule();
}
if (pid_ns->reboot)
current->signal->group_exit_code = pid_ns->reboot;

548
kernel/printk.c
View File

@@ -193,12 +193,19 @@ static int console_may_schedule;
* separated by ',', and find the message after the ';' character.
*/
enum log_flags {
LOG_DEFAULT = 0,
LOG_NOCONS = 1, /* already flushed, do not print to console */
};
struct log {
u64 ts_nsec; /* timestamp in nanoseconds */
u16 len; /* length of entire record */
u16 text_len; /* length of text buffer */
u16 dict_len; /* length of dictionary buffer */
u16 level; /* syslog level + facility */
u8 facility; /* syslog facility */
u8 flags:5; /* internal record flags */
u8 level:3; /* syslog level */
};
/*
@@ -227,10 +234,10 @@ static u32 clear_idx;
#define LOG_LINE_MAX 1024
/* record buffer */
#if !defined(CONFIG_64BIT) || defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
#define LOG_ALIGN 4
#else
#define LOG_ALIGN 8
#define LOG_ALIGN __alignof__(struct log)
#endif
#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
@@ -286,6 +293,7 @@ static u32 log_next(u32 idx)
/* insert record into the buffer, discard old ones, update heads */
static void log_store(int facility, int level,
enum log_flags flags, u64 ts_nsec,
const char *dict, u16 dict_len,
const char *text, u16 text_len)
{
@@ -329,8 +337,13 @@ static void log_store(int facility, int level,
msg->text_len = text_len;
memcpy(log_dict(msg), dict, dict_len);
msg->dict_len = dict_len;
msg->level = (facility << 3) | (level & 7);
msg->ts_nsec = local_clock();
msg->facility = facility;
msg->level = level & 7;
msg->flags = flags & 0x1f;
if (ts_nsec > 0)
msg->ts_nsec = ts_nsec;
else
msg->ts_nsec = local_clock();
memset(log_dict(msg) + dict_len, 0, pad_len);
msg->len = sizeof(struct log) + text_len + dict_len + pad_len;
@@ -414,7 +427,9 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
if (!user)
return -EBADF;
mutex_lock(&user->lock);
ret = mutex_lock_interruptible(&user->lock);
if (ret)
return ret;
raw_spin_lock(&logbuf_lock);
while (user->seq == log_next_seq) {
if (file->f_flags & O_NONBLOCK) {
@@ -444,7 +459,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
ts_usec = msg->ts_nsec;
do_div(ts_usec, 1000);
len = sprintf(user->buf, "%u,%llu,%llu;",
msg->level, user->seq, ts_usec);
(msg->facility << 3) | msg->level, user->seq, ts_usec);
/* escape non-printable characters */
for (i = 0; i < msg->text_len; i++) {
@@ -785,6 +800,21 @@ static bool printk_time;
#endif
module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
static size_t print_time(u64 ts, char *buf)
{
unsigned long rem_nsec;
if (!printk_time)
return 0;
if (!buf)
return 15;
rem_nsec = do_div(ts, 1000000000);
return sprintf(buf, "[%5lu.%06lu] ",
(unsigned long)ts, rem_nsec / 1000);
}
static size_t print_prefix(const struct log *msg, bool syslog, char *buf)
{
size_t len = 0;
@@ -801,18 +831,7 @@ static size_t print_prefix(const struct log *msg, bool syslog, char *buf)
}
}
if (printk_time) {
if (buf) {
unsigned long long ts = msg->ts_nsec;
unsigned long rem_nsec = do_div(ts, 1000000000);
len += sprintf(buf + len, "[%5lu.%06lu] ",
(unsigned long) ts, rem_nsec / 1000);
} else {
len += 15;
}
}
len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
return len;
}
@@ -860,26 +879,49 @@ static int syslog_print(char __user *buf, int size)
{
char *text;
struct log *msg;
int len;
int len = 0;
text = kmalloc(LOG_LINE_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
raw_spin_lock_irq(&logbuf_lock);
if (syslog_seq < log_first_seq) {
/* messages are gone, move to first one */
syslog_seq = log_first_seq;
syslog_idx = log_first_idx;
}
msg = log_from_idx(syslog_idx);
len = msg_print_text(msg, true, text, LOG_LINE_MAX);
syslog_idx = log_next(syslog_idx);
syslog_seq++;
raw_spin_unlock_irq(&logbuf_lock);
while (size > 0) {
size_t n;
if (len > 0 && copy_to_user(buf, text, len))
len = -EFAULT;
raw_spin_lock_irq(&logbuf_lock);
if (syslog_seq < log_first_seq) {
/* messages are gone, move to first one */
syslog_seq = log_first_seq;
syslog_idx = log_first_idx;
}
if (syslog_seq == log_next_seq) {
raw_spin_unlock_irq(&logbuf_lock);
break;
}
msg = log_from_idx(syslog_idx);
n = msg_print_text(msg, true, text, LOG_LINE_MAX);
if (n <= size) {
syslog_idx = log_next(syslog_idx);
syslog_seq++;
} else
n = 0;
raw_spin_unlock_irq(&logbuf_lock);
if (!n)
break;
len += n;
size -= n;
buf += n;
n = copy_to_user(buf - n, text, n);
if (n) {
len -= n;
if (!len)
len = -EFAULT;
break;
}
}
kfree(text);
return len;
@@ -909,7 +951,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
/*
* Find first record that fits, including all following records,
* into the user-provided buffer for this dump.
*/
*/
seq = clear_seq;
idx = clear_idx;
while (seq < log_next_seq) {
@@ -919,6 +961,8 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
idx = log_next(idx);
seq++;
}
/* move first record forward until length fits into the buffer */
seq = clear_seq;
idx = clear_idx;
while (len > size && seq < log_next_seq) {
@@ -929,7 +973,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
seq++;
}
/* last message in this dump */
/* last message fitting into this dump */
next_seq = log_next_seq;
len = 0;
@@ -974,6 +1018,7 @@ int do_syslog(int type, char __user *buf, int len, bool from_file)
{
bool clear = false;
static int saved_console_loglevel = -1;
static DEFINE_MUTEX(syslog_mutex);
int error;
error = check_syslog_permissions(type, from_file);
@@ -1000,11 +1045,17 @@ int do_syslog(int type, char __user *buf, int len, bool from_file)
error = -EFAULT;
goto out;
}
error = wait_event_interruptible(log_wait,
syslog_seq != log_next_seq);
error = mutex_lock_interruptible(&syslog_mutex);
if (error)
goto out;
error = wait_event_interruptible(log_wait,
syslog_seq != log_next_seq);
if (error) {
mutex_unlock(&syslog_mutex);
goto out;
}
error = syslog_print(buf, len);
mutex_unlock(&syslog_mutex);
break;
/* Read/clear last kernel messages */
case SYSLOG_ACTION_READ_CLEAR:
@@ -1027,6 +1078,7 @@ int do_syslog(int type, char __user *buf, int len, bool from_file)
/* Clear ring buffer */
case SYSLOG_ACTION_CLEAR:
syslog_print_all(NULL, 0, true);
break;
/* Disable logging to console */
case SYSLOG_ACTION_CONSOLE_OFF:
if (saved_console_loglevel == -1)
@@ -1259,15 +1311,92 @@ static inline void printk_delay(void)
}
}
/*
* Continuation lines are buffered, and not committed to the record buffer
* until the line is complete, or a race forces it. The line fragments
* though, are printed immediately to the consoles to ensure everything has
* reached the console in case of a kernel crash.
*/
static struct cont {
char buf[LOG_LINE_MAX];
size_t len; /* length == 0 means unused buffer */
size_t cons; /* bytes written to console */
struct task_struct *owner; /* task of first print*/
u64 ts_nsec; /* time of first print */
u8 level; /* log level of first message */
u8 facility; /* log level of first message */
bool flushed:1; /* buffer sealed and committed */
} cont;
static void cont_flush(void)
{
if (cont.flushed)
return;
if (cont.len == 0)
return;
log_store(cont.facility, cont.level, LOG_NOCONS, cont.ts_nsec,
NULL, 0, cont.buf, cont.len);
cont.flushed = true;
}
static bool cont_add(int facility, int level, const char *text, size_t len)
{
if (cont.len && cont.flushed)
return false;
if (cont.len + len > sizeof(cont.buf)) {
cont_flush();
return false;
}
if (!cont.len) {
cont.facility = facility;
cont.level = level;
cont.owner = current;
cont.ts_nsec = local_clock();
cont.cons = 0;
cont.flushed = false;
}
memcpy(cont.buf + cont.len, text, len);
cont.len += len;
return true;
}
static size_t cont_print_text(char *text, size_t size)
{
size_t textlen = 0;
size_t len;
if (cont.cons == 0) {
textlen += print_time(cont.ts_nsec, text);
size -= textlen;
}
len = cont.len - cont.cons;
if (len > 0) {
if (len+1 > size)
len = size-1;
memcpy(text + textlen, cont.buf + cont.cons, len);
textlen += len;
cont.cons = cont.len;
}
if (cont.flushed) {
text[textlen++] = '\n';
/* got everything, release buffer */
cont.len = 0;
}
return textlen;
}
asmlinkage int vprintk_emit(int facility, int level,
const char *dict, size_t dictlen,
const char *fmt, va_list args)
{
static int recursion_bug;
static char cont_buf[LOG_LINE_MAX];
static size_t cont_len;
static int cont_level;
static struct task_struct *cont_task;
static char textbuf[LOG_LINE_MAX];
char *text = textbuf;
size_t text_len;
@@ -1313,7 +1442,8 @@ asmlinkage int vprintk_emit(int facility, int level,
recursion_bug = 0;
printed_len += strlen(recursion_msg);
/* emit KERN_CRIT message */
log_store(0, 2, NULL, 0, recursion_msg, printed_len);
log_store(0, 2, LOG_DEFAULT, 0,
NULL, 0, recursion_msg, printed_len);
}
/*
@@ -1351,55 +1481,37 @@ asmlinkage int vprintk_emit(int facility, int level,
}
if (!newline) {
if (cont_len && (prefix || cont_task != current)) {
/*
* Flush earlier buffer, which is either from a
* different thread, or when we got a new prefix.
*/
log_store(facility, cont_level, NULL, 0, cont_buf, cont_len);
cont_len = 0;
}
/*
* Flush the conflicting buffer. An earlier newline was missing,
* or another task also prints continuation lines.
*/
if (cont.len && (prefix || cont.owner != current))
cont_flush();
if (!cont_len) {
cont_level = level;
cont_task = current;
}
/* buffer or append to earlier buffer from the same thread */
if (cont_len + text_len > sizeof(cont_buf))
text_len = sizeof(cont_buf) - cont_len;
memcpy(cont_buf + cont_len, text, text_len);
cont_len += text_len;
} else {
if (cont_len && cont_task == current) {
if (prefix) {
/*
* New prefix from the same thread; flush. We
* either got no earlier newline, or we race
* with an interrupt.
*/
log_store(facility, cont_level,
NULL, 0, cont_buf, cont_len);
cont_len = 0;
}
/* append to the earlier buffer and flush */
if (cont_len + text_len > sizeof(cont_buf))
text_len = sizeof(cont_buf) - cont_len;
memcpy(cont_buf + cont_len, text, text_len);
cont_len += text_len;
log_store(facility, cont_level,
NULL, 0, cont_buf, cont_len);
cont_len = 0;
cont_task = NULL;
printed_len = cont_len;
} else {
/* ordinary single and terminated line */
log_store(facility, level,
/* buffer line if possible, otherwise store it right away */
if (!cont_add(facility, level, text, text_len))
log_store(facility, level, LOG_DEFAULT, 0,
dict, dictlen, text, text_len);
printed_len = text_len;
} else {
bool stored = false;
/*
* If an earlier newline was missing and it was the same task,
* either merge it with the current buffer and flush, or if
* there was a race with interrupts (prefix == true) then just
* flush it out and store this line separately.
*/
if (cont.len && cont.owner == current) {
if (!prefix)
stored = cont_add(facility, level, text, text_len);
cont_flush();
}
if (!stored)
log_store(facility, level, LOG_DEFAULT, 0,
dict, dictlen, text, text_len);
}
printed_len += text_len;
/*
* Try to acquire and then immediately release the console semaphore.
@@ -1486,11 +1598,18 @@ EXPORT_SYMBOL(printk);
#else
#define LOG_LINE_MAX 0
static struct cont {
size_t len;
size_t cons;
u8 level;
bool flushed:1;
} cont;
static struct log *log_from_idx(u32 idx) { return NULL; }
static u32 log_next(u32 idx) { return 0; }
static void call_console_drivers(int level, const char *text, size_t len) {}
static size_t msg_print_text(const struct log *msg, bool syslog,
char *buf, size_t size) { return 0; }
static size_t cont_print_text(char *text, size_t size) { return 0; }
#endif /* CONFIG_PRINTK */
@@ -1782,6 +1901,7 @@ static u32 console_idx;
*/
void console_unlock(void)
{
static char text[LOG_LINE_MAX];
static u64 seen_seq;
unsigned long flags;
bool wake_klogd = false;
@@ -1794,10 +1914,23 @@ void console_unlock(void)
console_may_schedule = 0;
/* flush buffered message fragment immediately to console */
raw_spin_lock_irqsave(&logbuf_lock, flags);
if (cont.len && (cont.cons < cont.len || cont.flushed)) {
size_t len;
len = cont_print_text(text, sizeof(text));
raw_spin_unlock(&logbuf_lock);
stop_critical_timings();
call_console_drivers(cont.level, text, len);
start_critical_timings();
local_irq_restore(flags);
} else
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
again:
for (;;) {
struct log *msg;
static char text[LOG_LINE_MAX];
size_t len;
int level;
@@ -1812,13 +1945,22 @@ again:
console_seq = log_first_seq;
console_idx = log_first_idx;
}
skip:
if (console_seq == log_next_seq)
break;
msg = log_from_idx(console_idx);
level = msg->level & 7;
if (msg->flags & LOG_NOCONS) {
/*
* Skip record we have buffered and already printed
* directly to the console when we received it.
*/
console_idx = log_next(console_idx);
console_seq++;
goto skip;
}
level = msg->level;
len = msg_print_text(msg, false, text, sizeof(text));
console_idx = log_next(console_idx);
@@ -2300,48 +2442,210 @@ module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR);
* kmsg_dump - dump kernel log to kernel message dumpers.
* @reason: the reason (oops, panic etc) for dumping
*
* Iterate through each of the dump devices and call the oops/panic
* callbacks with the log buffer.
* Call each of the registered dumper's dump() callback, which can
* retrieve the kmsg records with kmsg_dump_get_line() or
* kmsg_dump_get_buffer().
*/
void kmsg_dump(enum kmsg_dump_reason reason)
{
u64 idx;
struct kmsg_dumper *dumper;
const char *s1, *s2;
unsigned long l1, l2;
unsigned long flags;
if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
return;
/* Theoretically, the log could move on after we do this, but
there's not a lot we can do about that. The new messages
will overwrite the start of what we dump. */
raw_spin_lock_irqsave(&logbuf_lock, flags);
if (syslog_seq < log_first_seq)
idx = syslog_idx;
else
idx = log_first_idx;
if (idx > log_next_idx) {
s1 = log_buf;
l1 = log_next_idx;
s2 = log_buf + idx;
l2 = log_buf_len - idx;
} else {
s1 = "";
l1 = 0;
s2 = log_buf + idx;
l2 = log_next_idx - idx;
}
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
rcu_read_lock();
list_for_each_entry_rcu(dumper, &dump_list, list)
dumper->dump(dumper, reason, s1, l1, s2, l2);
list_for_each_entry_rcu(dumper, &dump_list, list) {
if (dumper->max_reason && reason > dumper->max_reason)
continue;
/* initialize iterator with data about the stored records */
dumper->active = true;
raw_spin_lock_irqsave(&logbuf_lock, flags);
dumper->cur_seq = clear_seq;
dumper->cur_idx = clear_idx;
dumper->next_seq = log_next_seq;
dumper->next_idx = log_next_idx;
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
/* invoke dumper which will iterate over records */
dumper->dump(dumper, reason);
/* reset iterator */
dumper->active = false;
}
rcu_read_unlock();
}
/**
* kmsg_dump_get_line - retrieve one kmsg log line
* @dumper: registered kmsg dumper
* @syslog: include the "<4>" prefixes
* @line: buffer to copy the line to
* @size: maximum size of the buffer
* @len: length of line placed into buffer
*
* Start at the beginning of the kmsg buffer, with the oldest kmsg
* record, and copy one record into the provided buffer.
*
* Consecutive calls will return the next available record moving
* towards the end of the buffer with the youngest messages.
*
* A return value of FALSE indicates that there are no more records to
* read.
*/
bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
char *line, size_t size, size_t *len)
{
unsigned long flags;
struct log *msg;
size_t l = 0;
bool ret = false;
if (!dumper->active)
goto out;
raw_spin_lock_irqsave(&logbuf_lock, flags);
if (dumper->cur_seq < log_first_seq) {
/* messages are gone, move to first available one */
dumper->cur_seq = log_first_seq;
dumper->cur_idx = log_first_idx;
}
/* last entry */
if (dumper->cur_seq >= log_next_seq) {
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
goto out;
}
msg = log_from_idx(dumper->cur_idx);
l = msg_print_text(msg, syslog,
line, size);
dumper->cur_idx = log_next(dumper->cur_idx);
dumper->cur_seq++;
ret = true;
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
out:
if (len)
*len = l;
return ret;
}
EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
/**
* kmsg_dump_get_buffer - copy kmsg log lines
* @dumper: registered kmsg dumper
* @syslog: include the "<4>" prefixes
* @buf: buffer to copy the line to
* @size: maximum size of the buffer
* @len: length of line placed into buffer
*
* Start at the end of the kmsg buffer and fill the provided buffer
* with as many of the the *youngest* kmsg records that fit into it.
* If the buffer is large enough, all available kmsg records will be
* copied with a single call.
*
* Consecutive calls will fill the buffer with the next block of
* available older records, not including the earlier retrieved ones.
*
* A return value of FALSE indicates that there are no more records to
* read.
*/
bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
char *buf, size_t size, size_t *len)
{
unsigned long flags;
u64 seq;
u32 idx;
u64 next_seq;
u32 next_idx;
size_t l = 0;
bool ret = false;
if (!dumper->active)
goto out;
raw_spin_lock_irqsave(&logbuf_lock, flags);
if (dumper->cur_seq < log_first_seq) {
/* messages are gone, move to first available one */
dumper->cur_seq = log_first_seq;
dumper->cur_idx = log_first_idx;
}
/* last entry */
if (dumper->cur_seq >= dumper->next_seq) {
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
goto out;
}
/* calculate length of entire buffer */
seq = dumper->cur_seq;
idx = dumper->cur_idx;
while (seq < dumper->next_seq) {
struct log *msg = log_from_idx(idx);
l += msg_print_text(msg, true, NULL, 0);
idx = log_next(idx);
seq++;
}
/* move first record forward until length fits into the buffer */
seq = dumper->cur_seq;
idx = dumper->cur_idx;
while (l > size && seq < dumper->next_seq) {
struct log *msg = log_from_idx(idx);
l -= msg_print_text(msg, true, NULL, 0);
idx = log_next(idx);
seq++;
}
/* last message in next interation */
next_seq = seq;
next_idx = idx;
l = 0;
while (seq < dumper->next_seq) {
struct log *msg = log_from_idx(idx);
l += msg_print_text(msg, syslog,
buf + l, size - l);
idx = log_next(idx);
seq++;
}
dumper->next_seq = next_seq;
dumper->next_idx = next_idx;
ret = true;
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
out:
if (len)
*len = l;
return ret;
}
EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
/**
* kmsg_dump_rewind - reset the interator
* @dumper: registered kmsg dumper
*
* Reset the dumper's iterator so that kmsg_dump_get_line() and
* kmsg_dump_get_buffer() can be called again and used multiple
* times within the same dumper.dump() callback.
*/
void kmsg_dump_rewind(struct kmsg_dumper *dumper)
{
unsigned long flags;
raw_spin_lock_irqsave(&logbuf_lock, flags);
dumper->cur_seq = clear_seq;
dumper->cur_idx = clear_idx;
dumper->next_seq = log_next_seq;
dumper->next_idx = log_next_idx;
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
}
EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
#endif

16
kernel/rcutree.c
View File

@@ -1397,6 +1397,8 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
rdp->qlen_lazy += rsp->qlen_lazy;
rdp->qlen += rsp->qlen;
rdp->n_cbs_adopted += rsp->qlen;
if (rsp->qlen_lazy != rsp->qlen)
rcu_idle_count_callbacks_posted();
rsp->qlen_lazy = 0;
rsp->qlen = 0;
@@ -1528,7 +1530,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
{
unsigned long flags;
struct rcu_head *next, *list, **tail;
int bl, count, count_lazy;
int bl, count, count_lazy, i;
/* If no callbacks are ready, just return.*/
if (!cpu_has_callbacks_ready_to_invoke(rdp)) {
@@ -1551,9 +1553,9 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL];
*rdp->nxttail[RCU_DONE_TAIL] = NULL;
tail = rdp->nxttail[RCU_DONE_TAIL];
for (count = RCU_NEXT_SIZE - 1; count >= 0; count--)
if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL])
rdp->nxttail[count] = &rdp->nxtlist;
for (i = RCU_NEXT_SIZE - 1; i >= 0; i--)
if (rdp->nxttail[i] == rdp->nxttail[RCU_DONE_TAIL])
rdp->nxttail[i] = &rdp->nxtlist;
local_irq_restore(flags);
/* Invoke callbacks. */
@@ -1581,9 +1583,9 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
if (list != NULL) {
*tail = rdp->nxtlist;
rdp->nxtlist = list;
for (count = 0; count < RCU_NEXT_SIZE; count++)
if (&rdp->nxtlist == rdp->nxttail[count])
rdp->nxttail[count] = tail;
for (i = 0; i < RCU_NEXT_SIZE; i++)
if (&rdp->nxtlist == rdp->nxttail[i])
rdp->nxttail[i] = tail;
else
break;
}

14
kernel/rcutree.h
View File

@@ -84,6 +84,20 @@ struct rcu_dynticks {
/* Process level is worth LLONG_MAX/2. */
int dynticks_nmi_nesting; /* Track NMI nesting level. */
atomic_t dynticks; /* Even value for idle, else odd. */
#ifdef CONFIG_RCU_FAST_NO_HZ
int dyntick_drain; /* Prepare-for-idle state variable. */
unsigned long dyntick_holdoff;
/* No retries for the jiffy of failure. */
struct timer_list idle_gp_timer;
/* Wake up CPU sleeping with callbacks. */
unsigned long idle_gp_timer_expires;
/* When to wake up CPU (for repost). */
bool idle_first_pass; /* First pass of attempt to go idle? */
unsigned long nonlazy_posted;
/* # times non-lazy CBs posted to CPU. */
unsigned long nonlazy_posted_snap;
/* idle-period nonlazy_posted snapshot. */
#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
};
/* RCU's kthread states for tracing. */

165
kernel/rcutree_plugin.h
View File

@@ -1886,8 +1886,9 @@ static void __cpuinit rcu_prepare_kthreads(int cpu)
* Because we not have RCU_FAST_NO_HZ, just check whether this CPU needs
* any flavor of RCU.
*/
int rcu_needs_cpu(int cpu)
int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
{
*delta_jiffies = ULONG_MAX;
return rcu_cpu_has_callbacks(cpu);
}
@@ -1962,41 +1963,6 @@ static void rcu_idle_count_callbacks_posted(void)
#define RCU_IDLE_GP_DELAY 6 /* Roughly one grace period. */
#define RCU_IDLE_LAZY_GP_DELAY (6 * HZ) /* Roughly six seconds. */
/* Loop counter for rcu_prepare_for_idle(). */
static DEFINE_PER_CPU(int, rcu_dyntick_drain);
/* If rcu_dyntick_holdoff==jiffies, don't try to enter dyntick-idle mode. */
static DEFINE_PER_CPU(unsigned long, rcu_dyntick_holdoff);
/* Timer to awaken the CPU if it enters dyntick-idle mode with callbacks. */
static DEFINE_PER_CPU(struct timer_list, rcu_idle_gp_timer);
/* Scheduled expiry time for rcu_idle_gp_timer to allow reposting. */
static DEFINE_PER_CPU(unsigned long, rcu_idle_gp_timer_expires);
/* Enable special processing on first attempt to enter dyntick-idle mode. */
static DEFINE_PER_CPU(bool, rcu_idle_first_pass);
/* Running count of non-lazy callbacks posted, never decremented. */
static DEFINE_PER_CPU(unsigned long, rcu_nonlazy_posted);
/* Snapshot of rcu_nonlazy_posted to detect meaningful exits from idle. */
static DEFINE_PER_CPU(unsigned long, rcu_nonlazy_posted_snap);
/*
* Allow the CPU to enter dyntick-idle mode if either: (1) There are no
* callbacks on this CPU, (2) this CPU has not yet attempted to enter
* dyntick-idle mode, or (3) this CPU is in the process of attempting to
* enter dyntick-idle mode. Otherwise, if we have recently tried and failed
* to enter dyntick-idle mode, we refuse to try to enter it. After all,
* it is better to incur scheduling-clock interrupts than to spin
* continuously for the same time duration!
*/
int rcu_needs_cpu(int cpu)
{
/* Flag a new idle sojourn to the idle-entry state machine. */
per_cpu(rcu_idle_first_pass, cpu) = 1;
/* If no callbacks, RCU doesn't need the CPU. */
if (!rcu_cpu_has_callbacks(cpu))
return 0;
/* Otherwise, RCU needs the CPU only if it recently tried and failed. */
return per_cpu(rcu_dyntick_holdoff, cpu) == jiffies;
}
/*
* Does the specified flavor of RCU have non-lazy callbacks pending on
* the specified CPU? Both RCU flavor and CPU are specified by the
@@ -2039,6 +2005,47 @@ static bool rcu_cpu_has_nonlazy_callbacks(int cpu)
rcu_preempt_cpu_has_nonlazy_callbacks(cpu);
}
/*
* Allow the CPU to enter dyntick-idle mode if either: (1) There are no
* callbacks on this CPU, (2) this CPU has not yet attempted to enter
* dyntick-idle mode, or (3) this CPU is in the process of attempting to
* enter dyntick-idle mode. Otherwise, if we have recently tried and failed
* to enter dyntick-idle mode, we refuse to try to enter it. After all,
* it is better to incur scheduling-clock interrupts than to spin
* continuously for the same time duration!
*
* The delta_jiffies argument is used to store the time when RCU is
* going to need the CPU again if it still has callbacks. The reason
* for this is that rcu_prepare_for_idle() might need to post a timer,
* but if so, it will do so after tick_nohz_stop_sched_tick() has set
* the wakeup time for this CPU. This means that RCU's timer can be
* delayed until the wakeup time, which defeats the purpose of posting
* a timer.
*/
int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
{
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
/* Flag a new idle sojourn to the idle-entry state machine. */
rdtp->idle_first_pass = 1;
/* If no callbacks, RCU doesn't need the CPU. */
if (!rcu_cpu_has_callbacks(cpu)) {
*delta_jiffies = ULONG_MAX;
return 0;
}
if (rdtp->dyntick_holdoff == jiffies) {
/* RCU recently tried and failed, so don't try again. */
*delta_jiffies = 1;
return 1;
}
/* Set up for the possibility that RCU will post a timer. */
if (rcu_cpu_has_nonlazy_callbacks(cpu))
*delta_jiffies = RCU_IDLE_GP_DELAY;
else
*delta_jiffies = RCU_IDLE_LAZY_GP_DELAY;
return 0;
}
/*
* Handler for smp_call_function_single(). The only point of this
* handler is to wake the CPU up, so the handler does only tracing.
@@ -2075,21 +2082,24 @@ static void rcu_idle_gp_timer_func(unsigned long cpu_in)
*/
static void rcu_prepare_for_idle_init(int cpu)
{
per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1;
setup_timer(&per_cpu(rcu_idle_gp_timer, cpu),
rcu_idle_gp_timer_func, cpu);
per_cpu(rcu_idle_gp_timer_expires, cpu) = jiffies - 1;
per_cpu(rcu_idle_first_pass, cpu) = 1;
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
rdtp->dyntick_holdoff = jiffies - 1;
setup_timer(&rdtp->idle_gp_timer, rcu_idle_gp_timer_func, cpu);
rdtp->idle_gp_timer_expires = jiffies - 1;
rdtp->idle_first_pass = 1;
}
/*
* Clean up for exit from idle. Because we are exiting from idle, there
* is no longer any point to rcu_idle_gp_timer, so cancel it. This will
* is no longer any point to ->idle_gp_timer, so cancel it. This will
* do nothing if this timer is not active, so just cancel it unconditionally.
*/
static void rcu_cleanup_after_idle(int cpu)
{
del_timer(&per_cpu(rcu_idle_gp_timer, cpu));
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
del_timer(&rdtp->idle_gp_timer);
trace_rcu_prep_idle("Cleanup after idle");
}
@@ -2108,42 +2118,41 @@ static void rcu_cleanup_after_idle(int cpu)
* Because it is not legal to invoke rcu_process_callbacks() with irqs
* disabled, we do one pass of force_quiescent_state(), then do a
* invoke_rcu_core() to cause rcu_process_callbacks() to be invoked
* later. The per-cpu rcu_dyntick_drain variable controls the sequencing.
* later. The ->dyntick_drain field controls the sequencing.
*
* The caller must have disabled interrupts.
*/
static void rcu_prepare_for_idle(int cpu)
{
struct timer_list *tp;
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
/*
* If this is an idle re-entry, for example, due to use of
* RCU_NONIDLE() or the new idle-loop tracing API within the idle
* loop, then don't take any state-machine actions, unless the
* momentary exit from idle queued additional non-lazy callbacks.
* Instead, repost the rcu_idle_gp_timer if this CPU has callbacks
* Instead, repost the ->idle_gp_timer if this CPU has callbacks
* pending.
*/
if (!per_cpu(rcu_idle_first_pass, cpu) &&
(per_cpu(rcu_nonlazy_posted, cpu) ==
per_cpu(rcu_nonlazy_posted_snap, cpu))) {
if (!rdtp->idle_first_pass &&
(rdtp->nonlazy_posted == rdtp->nonlazy_posted_snap)) {
if (rcu_cpu_has_callbacks(cpu)) {
tp = &per_cpu(rcu_idle_gp_timer, cpu);
mod_timer_pinned(tp, per_cpu(rcu_idle_gp_timer_expires, cpu));
tp = &rdtp->idle_gp_timer;
mod_timer_pinned(tp, rdtp->idle_gp_timer_expires);
}
return;
}
per_cpu(rcu_idle_first_pass, cpu) = 0;
per_cpu(rcu_nonlazy_posted_snap, cpu) =
per_cpu(rcu_nonlazy_posted, cpu) - 1;
rdtp->idle_first_pass = 0;
rdtp->nonlazy_posted_snap = rdtp->nonlazy_posted - 1;
/*
* If there are no callbacks on this CPU, enter dyntick-idle mode.
* Also reset state to avoid prejudicing later attempts.
*/
if (!rcu_cpu_has_callbacks(cpu)) {
per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1;
per_cpu(rcu_dyntick_drain, cpu) = 0;
rdtp->dyntick_holdoff = jiffies - 1;
rdtp->dyntick_drain = 0;
trace_rcu_prep_idle("No callbacks");
return;
}
@@ -2152,36 +2161,37 @@ static void rcu_prepare_for_idle(int cpu)
* If in holdoff mode, just return. We will presumably have
* refrained from disabling the scheduling-clock tick.
*/
if (per_cpu(rcu_dyntick_holdoff, cpu) == jiffies) {
if (rdtp->dyntick_holdoff == jiffies) {
trace_rcu_prep_idle("In holdoff");
return;
}
/* Check and update the rcu_dyntick_drain sequencing. */
if (per_cpu(rcu_dyntick_drain, cpu) <= 0) {
/* Check and update the ->dyntick_drain sequencing. */
if (rdtp->dyntick_drain <= 0) {
/* First time through, initialize the counter. */
per_cpu(rcu_dyntick_drain, cpu) = RCU_IDLE_FLUSHES;
} else if (per_cpu(rcu_dyntick_drain, cpu) <= RCU_IDLE_OPT_FLUSHES &&
rdtp->dyntick_drain = RCU_IDLE_FLUSHES;
} else if (rdtp->dyntick_drain <= RCU_IDLE_OPT_FLUSHES &&
!rcu_pending(cpu) &&
!local_softirq_pending()) {
/* Can we go dyntick-idle despite still having callbacks? */
trace_rcu_prep_idle("Dyntick with callbacks");
per_cpu(rcu_dyntick_drain, cpu) = 0;
per_cpu(rcu_dyntick_holdoff, cpu) = jiffies;
if (rcu_cpu_has_nonlazy_callbacks(cpu))
per_cpu(rcu_idle_gp_timer_expires, cpu) =
rdtp->dyntick_drain = 0;
rdtp->dyntick_holdoff = jiffies;
if (rcu_cpu_has_nonlazy_callbacks(cpu)) {
trace_rcu_prep_idle("Dyntick with callbacks");
rdtp->idle_gp_timer_expires =
jiffies + RCU_IDLE_GP_DELAY;
else
per_cpu(rcu_idle_gp_timer_expires, cpu) =
} else {
rdtp->idle_gp_timer_expires =
jiffies + RCU_IDLE_LAZY_GP_DELAY;
tp = &per_cpu(rcu_idle_gp_timer, cpu);
mod_timer_pinned(tp, per_cpu(rcu_idle_gp_timer_expires, cpu));
per_cpu(rcu_nonlazy_posted_snap, cpu) =
per_cpu(rcu_nonlazy_posted, cpu);
trace_rcu_prep_idle("Dyntick with lazy callbacks");
}
tp = &rdtp->idle_gp_timer;
mod_timer_pinned(tp, rdtp->idle_gp_timer_expires);
rdtp->nonlazy_posted_snap = rdtp->nonlazy_posted;
return; /* Nothing more to do immediately. */
} else if (--per_cpu(rcu_dyntick_drain, cpu) <= 0) {
} else if (--(rdtp->dyntick_drain) <= 0) {
/* We have hit the limit, so time to give up. */
per_cpu(rcu_dyntick_holdoff, cpu) = jiffies;
rdtp->dyntick_holdoff = jiffies;
trace_rcu_prep_idle("Begin holdoff");
invoke_rcu_core(); /* Force the CPU out of dyntick-idle. */
return;
@@ -2227,7 +2237,7 @@ static void rcu_prepare_for_idle(int cpu)
*/
static void rcu_idle_count_callbacks_posted(void)
{
__this_cpu_add(rcu_nonlazy_posted, 1);
__this_cpu_add(rcu_dynticks.nonlazy_posted, 1);
}
#endif /* #else #if !defined(CONFIG_RCU_FAST_NO_HZ) */
@@ -2238,11 +2248,12 @@ static void rcu_idle_count_callbacks_posted(void)
static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
{
struct timer_list *tltp = &per_cpu(rcu_idle_gp_timer, cpu);
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
struct timer_list *tltp = &rdtp->idle_gp_timer;
sprintf(cp, "drain=%d %c timer=%lu",
per_cpu(rcu_dyntick_drain, cpu),
per_cpu(rcu_dyntick_holdoff, cpu) == jiffies ? 'H' : '.',
rdtp->dyntick_drain,
rdtp->dyntick_holdoff == jiffies ? 'H' : '.',
timer_pending(tltp) ? tltp->expires - jiffies : -1);
}

5
kernel/relay.c
View File

@@ -1235,6 +1235,7 @@ static ssize_t subbuf_splice_actor(struct file *in,
struct splice_pipe_desc spd = {
.pages = pages,
.nr_pages = 0,
.nr_pages_max = PIPE_DEF_BUFFERS,
.partial = partial,
.flags = flags,
.ops = &relay_pipe_buf_ops,
@@ -1302,8 +1303,8 @@ static ssize_t subbuf_splice_actor(struct file *in,
ret += padding;
out:
splice_shrink_spd(pipe, &spd);
return ret;
splice_shrink_spd(&spd);
return ret;
}
static ssize_t relay_file_splice_read(struct file *in,

6
kernel/sys.c
View File

@@ -2127,9 +2127,6 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
else
return -EINVAL;
break;
case PR_GET_TID_ADDRESS:
error = prctl_get_tid_address(me, (int __user **)arg2);
break;
default:
return -EINVAL;
}
@@ -2147,6 +2144,9 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
case PR_SET_MM:
error = prctl_set_mm(arg2, arg3, arg4, arg5);
break;
case PR_GET_TID_ADDRESS:
error = prctl_get_tid_address(me, (int __user **)arg2);
break;
case PR_SET_CHILD_SUBREAPER:
me->signal->is_child_subreaper = !!arg2;
error = 0;

7
kernel/time/tick-sched.c
View File

@@ -274,6 +274,7 @@ EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us);
static void tick_nohz_stop_sched_tick(struct tick_sched *ts)
{
unsigned long seq, last_jiffies, next_jiffies, delta_jiffies;
unsigned long rcu_delta_jiffies;
ktime_t last_update, expires, now;
struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
u64 time_delta;
@@ -322,7 +323,7 @@ static void tick_nohz_stop_sched_tick(struct tick_sched *ts)
time_delta = timekeeping_max_deferment();
} while (read_seqretry(&xtime_lock, seq));
if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||
if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || printk_needs_cpu(cpu) ||
arch_needs_cpu(cpu)) {
next_jiffies = last_jiffies + 1;
delta_jiffies = 1;
@@ -330,6 +331,10 @@ static void tick_nohz_stop_sched_tick(struct tick_sched *ts)
/* Get the next timer wheel timer */
next_jiffies = get_next_timer_interrupt(last_jiffies);
delta_jiffies = next_jiffies - last_jiffies;
if (rcu_delta_jiffies < delta_jiffies) {
next_jiffies = last_jiffies + rcu_delta_jiffies;
delta_jiffies = rcu_delta_jiffies;
}
}
/*
* Do not stop the tick, if we are only one off

8
kernel/trace/trace.c
View File

@@ -371,7 +371,7 @@ EXPORT_SYMBOL_GPL(tracing_on);
void tracing_off(void)
{
if (global_trace.buffer)
ring_buffer_record_on(global_trace.buffer);
ring_buffer_record_off(global_trace.buffer);
/*
* This flag is only looked at when buffers haven't been
* allocated yet. We don't really care about the race
@@ -3609,6 +3609,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
.pages = pages_def,
.partial = partial_def,
.nr_pages = 0, /* This gets updated below. */
.nr_pages_max = PIPE_DEF_BUFFERS,
.flags = flags,
.ops = &tracing_pipe_buf_ops,
.spd_release = tracing_spd_release_pipe,
@@ -3680,7 +3681,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
ret = splice_to_pipe(pipe, &spd);
out:
splice_shrink_spd(pipe, &spd);
splice_shrink_spd(&spd);
return ret;
out_err:
@@ -4231,6 +4232,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
struct splice_pipe_desc spd = {
.pages = pages_def,
.partial = partial_def,
.nr_pages_max = PIPE_DEF_BUFFERS,
.flags = flags,
.ops = &buffer_pipe_buf_ops,
.spd_release = buffer_spd_release,
@@ -4318,7 +4320,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
}
ret = splice_to_pipe(pipe, &spd);
splice_shrink_spd(pipe, &spd);
splice_shrink_spd(&spd);
out:
return ret;
}

19
kernel/watchdog.c
View File

@@ -372,6 +372,13 @@ static int watchdog(void *unused)
#ifdef CONFIG_HARDLOCKUP_DETECTOR
/*
* People like the simple clean cpu node info on boot.
* Reduce the watchdog noise by only printing messages
* that are different from what cpu0 displayed.
*/
static unsigned long cpu0_err;
static int watchdog_nmi_enable(int cpu)
{
struct perf_event_attr *wd_attr;
@@ -390,11 +397,21 @@ static int watchdog_nmi_enable(int cpu)
/* Try to register using hardware perf events */
event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);
/* save cpu0 error for future comparision */
if (cpu == 0 && IS_ERR(event))
cpu0_err = PTR_ERR(event);
if (!IS_ERR(event)) {
pr_info("enabled, takes one hw-pmu counter.\n");
/* only print for cpu0 or different than cpu0 */
if (cpu == 0 || cpu0_err)
pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n");
goto out_save;
}
/* skip displaying the same error again */
if (cpu > 0 && (PTR_ERR(event) == cpu0_err))
return PTR_ERR(event);
/* vary the KERN level based on the returned errno */
if (PTR_ERR(event) == -EOPNOTSUPP)