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srcu: Prohibit call_srcu() use under raw spinlocks

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Invoking queue_delayed_work() while holding a raw spinlock is forbidden
in -rt kernels, which is exactly what __call_srcu() does, indirectly via
srcu_funnel_gp_start().  This commit therefore downgrades Tree SRCU's
locking from raw to non-raw spinlocks, which works because call_srcu()
is not ever called while holding a raw spinlock.

Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney
2017-10-10 13:52:30 -07:00
parent 4fbd8d194f
commit d633198088
2 changed files with 72 additions and 45 deletions
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8
include/linux/srcutree.h
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@@ -40,7 +40,7 @@ struct srcu_data {
unsigned long srcu_unlock_count[2]; /* Unlocks per CPU. */
/* Update-side state. */
raw_spinlock_t __private lock ____cacheline_internodealigned_in_smp;
spinlock_t __private lock ____cacheline_internodealigned_in_smp;
struct rcu_segcblist srcu_cblist; /* List of callbacks.*/
unsigned long srcu_gp_seq_needed; /* Furthest future GP needed. */
unsigned long srcu_gp_seq_needed_exp; /* Furthest future exp GP. */
@@ -58,7 +58,7 @@ struct srcu_data {
* Node in SRCU combining tree, similar in function to rcu_data.
*/
struct srcu_node {
raw_spinlock_t __private lock;
spinlock_t __private lock;
unsigned long srcu_have_cbs[4]; /* GP seq for children */
/* having CBs, but only */
/* is > ->srcu_gq_seq. */
@@ -78,7 +78,7 @@ struct srcu_struct {
struct srcu_node *level[RCU_NUM_LVLS + 1];
/* First node at each level. */
struct mutex srcu_cb_mutex; /* Serialize CB preparation. */
raw_spinlock_t __private lock; /* Protect counters */
spinlock_t __private lock; /* Protect counters */
struct mutex srcu_gp_mutex; /* Serialize GP work. */
unsigned int srcu_idx; /* Current rdr array element. */
unsigned long srcu_gp_seq; /* Grace-period seq #. */
@@ -107,7 +107,7 @@ struct srcu_struct {
#define __SRCU_STRUCT_INIT(name) \
{ \
.sda = &name##_srcu_data, \
.lock = __RAW_SPIN_LOCK_UNLOCKED(name.lock), \
.lock = __SPIN_LOCK_UNLOCKED(name.lock), \
.srcu_gp_seq_needed = 0 - 1, \
__SRCU_DEP_MAP_INIT(name) \
}