xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

kdb: Remove special case logic from kdb_read()

Browse Source 
kdb_read() contains special case logic to force it exit after reading
a single character. We can remove all the special case logic by directly
calling the function to read a single character instead. This also
allows us to tidy up the function prototype which, because it now matches
getchar(), we can also rename in order to make its role clearer.

This does involve some extra code to handle btaprompt properly but we
don't mind the new lines of code here because the old code had some
interesting problems (bad newline handling, treating unexpected
characters like <cr>).

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20191025073328.643-4-daniel.thompson@linaro.org
This commit is contained in:
Daniel Thompson
2019-10-25 08:33:26 +01:00
parent d04213af90
commit 4f27e824bf
3 changed files with 42 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

61
kernel/debug/kdb/kdb_io.c
View File

@@ -108,7 +108,22 @@ static int kdb_handle_escape(char *buf, size_t sz)
return -1;
}
static int kdb_read_get_key(char *buffer, size_t bufsize)
/**
* kdb_getchar() - Read a single character from a kdb console (or consoles).
*
* Other than polling the various consoles that are currently enabled,
* most of the work done in this function is dealing with escape sequences.
*
* An escape key could be the start of a vt100 control sequence such as \e[D
* (left arrow) or it could be a character in its own right. The standard
* method for detecting the difference is to wait for 2 seconds to see if there
* are any other characters. kdb is complicated by the lack of a timer service
* (interrupts are off), by multiple input sources. Escape sequence processing
* has to be done as states in the polling loop.
*
* Return: The key pressed or a control code derived from an escape sequence.
*/
char kdb_getchar(void)
{
#define ESCAPE_UDELAY 1000
#define ESCAPE_DELAY (2*1000000/ESCAPE_UDELAY) /* 2 seconds worth of udelays */
@@ -126,7 +141,6 @@ static int kdb_read_get_key(char *buffer, size_t bufsize)
}
key = (*f)();
if (key == -1) {
if (escape_delay) {
udelay(ESCAPE_UDELAY);
@@ -136,14 +150,6 @@ static int kdb_read_get_key(char *buffer, size_t bufsize)
continue;
}
if (bufsize <= 2) {
if (key == '\r')
key = '\n';
*buffer++ = key;
*buffer = '\0';
return -1;
}
if (escape_delay == 0 && key == '\e') {
escape_delay = ESCAPE_DELAY;
ped = escape_data;
@@ -184,17 +190,7 @@ static int kdb_read_get_key(char *buffer, size_t bufsize)
* function. It is not reentrant - it relies on the fact
* that while kdb is running on only one "master debug" cpu.
* Remarks:
*
* The buffer size must be >= 2. A buffer size of 2 means that the caller only
* wants a single key.
*
* An escape key could be the start of a vt100 control sequence such as \e[D
* (left arrow) or it could be a character in its own right. The standard
* method for detecting the difference is to wait for 2 seconds to see if there
* are any other characters. kdb is complicated by the lack of a timer service
* (interrupts are off), by multiple input sources and by the need to sometimes
* return after just one key. Escape sequence processing has to be done as
* states in the polling loop.
* The buffer size must be >= 2.
*/
static char *kdb_read(char *buffer, size_t bufsize)
@@ -229,9 +225,7 @@ static char *kdb_read(char *buffer, size_t bufsize)
*cp = '\0';
kdb_printf("%s", buffer);
poll_again:
key = kdb_read_get_key(buffer, bufsize);
if (key == -1)
return buffer;
key = kdb_getchar();
if (key != 9)
tab = 0;
switch (key) {
@@ -742,7 +736,7 @@ kdb_printit:
/* check for having reached the LINES number of printed lines */
if (kdb_nextline >= linecount) {
char buf1[16] = "";
char ch;
/* Watch out for recursion here. Any routine that calls
* kdb_printf will come back through here. And kdb_read
@@ -777,39 +771,38 @@ kdb_printit:
if (logging)
printk("%s", moreprompt);
kdb_read(buf1, 2); /* '2' indicates to return
* immediately after getting one key. */
ch = kdb_getchar();
kdb_nextline = 1; /* Really set output line 1 */
/* empty and reset the buffer: */
kdb_buffer[0] = '\0';
next_avail = kdb_buffer;
size_avail = sizeof(kdb_buffer);
if ((buf1[0] == 'q') || (buf1[0] == 'Q')) {
if ((ch == 'q') || (ch == 'Q')) {
/* user hit q or Q */
KDB_FLAG_SET(CMD_INTERRUPT); /* command interrupted */
KDB_STATE_CLEAR(PAGER);
/* end of command output; back to normal mode */
kdb_grepping_flag = 0;
kdb_printf("\n");
} else if (buf1[0] == ' ') {
} else if (ch == ' ') {
kdb_printf("\r");
suspend_grep = 1; /* for this recursion */
} else if (buf1[0] == '\n') {
} else if (ch == '\n' || ch == '\r') {
kdb_nextline = linecount - 1;
kdb_printf("\r");
suspend_grep = 1; /* for this recursion */
} else if (buf1[0] == '/' && !kdb_grepping_flag) {
} else if (ch == '/' && !kdb_grepping_flag) {
kdb_printf("\r");
kdb_getstr(kdb_grep_string, KDB_GREP_STRLEN,
kdbgetenv("SEARCHPROMPT") ?: "search> ");
*strchrnul(kdb_grep_string, '\n') = '\0';
kdb_grepping_flag += KDB_GREPPING_FLAG_SEARCH;
suspend_grep = 1; /* for this recursion */
} else if (buf1[0] && buf1[0] != '\n') {
/* user hit something other than enter */
} else if (ch) {
/* user hit something unexpected */
suspend_grep = 1; /* for this recursion */
if (buf1[0] != '/')
if (ch != '/')
kdb_printf(
"\nOnly 'q', 'Q' or '/' are processed at "
"more prompt, input ignored\n");