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Merge branch 'rcu-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull RCU fixes from Ingo Molnar:
 "Fix an SRCU bug affecting KVM IRQ injection"

* 'rcu-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  srcu: Allow use of Classic SRCU from both process and interrupt context
  srcu: Allow use of Tiny/Tree SRCU from both process and interrupt context
This commit is contained in:
Linus Torvalds 2017-06-10 10:22:35 -07:00
parent f701d860af 8affb06737
commit 6b7ed4588c
4 changed files with 8 additions and 11 deletions
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2
include/linux/srcu.h
View File

@ -172,9 +172,7 @@ static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
{ {
int retval; int retval;
preempt_disable();
retval = __srcu_read_lock(sp); retval = __srcu_read_lock(sp);
preempt_enable();
rcu_lock_acquire(&(sp)->dep_map); rcu_lock_acquire(&(sp)->dep_map);
return retval; return retval;
} }

5
kernel/rcu/srcu.c
View File

@ -263,7 +263,7 @@ EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
/* /*
* Counts the new reader in the appropriate per-CPU element of the * Counts the new reader in the appropriate per-CPU element of the
* srcu_struct. Must be called from process context. * srcu_struct.
* Returns an index that must be passed to the matching srcu_read_unlock(). * Returns an index that must be passed to the matching srcu_read_unlock().
*/ */
int __srcu_read_lock(struct srcu_struct *sp) int __srcu_read_lock(struct srcu_struct *sp)
@ -271,7 +271,7 @@ int __srcu_read_lock(struct srcu_struct *sp)
int idx; int idx;
idx = READ_ONCE(sp->completed) & 0x1; idx = READ_ONCE(sp->completed) & 0x1;
__this_cpu_inc(sp->per_cpu_ref->lock_count[idx]); this_cpu_inc(sp->per_cpu_ref->lock_count[idx]);
smp_mb(); /* B */ /* Avoid leaking the critical section. */ smp_mb(); /* B */ /* Avoid leaking the critical section. */
return idx; return idx;
} }
@ -281,7 +281,6 @@ EXPORT_SYMBOL_GPL(__srcu_read_lock);
* Removes the count for the old reader from the appropriate per-CPU * Removes the count for the old reader from the appropriate per-CPU
* element of the srcu_struct. Note that this may well be a different * element of the srcu_struct. Note that this may well be a different
* CPU than that which was incremented by the corresponding srcu_read_lock(). * CPU than that which was incremented by the corresponding srcu_read_lock().
* Must be called from process context.
*/ */
void __srcu_read_unlock(struct srcu_struct *sp, int idx) void __srcu_read_unlock(struct srcu_struct *sp, int idx)
{ {

7
kernel/rcu/srcutiny.c
View File

@ -97,8 +97,9 @@ EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
/* /*
* Counts the new reader in the appropriate per-CPU element of the * Counts the new reader in the appropriate per-CPU element of the
* srcu_struct. Must be called from process context. * srcu_struct. Can be invoked from irq/bh handlers, but the matching
* Returns an index that must be passed to the matching srcu_read_unlock(). * __srcu_read_unlock() must be in the same handler instance. Returns an
* index that must be passed to the matching srcu_read_unlock().
*/ */
int __srcu_read_lock(struct srcu_struct *sp) int __srcu_read_lock(struct srcu_struct *sp)
{ {
@ -112,7 +113,7 @@ EXPORT_SYMBOL_GPL(__srcu_read_lock);
/* /*
* Removes the count for the old reader from the appropriate element of * Removes the count for the old reader from the appropriate element of
* the srcu_struct. Must be called from process context. * the srcu_struct.
*/ */
void __srcu_read_unlock(struct srcu_struct *sp, int idx) void __srcu_read_unlock(struct srcu_struct *sp, int idx)
{ {

5
kernel/rcu/srcutree.c
View File

@ -357,7 +357,7 @@ EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
/* /*
* Counts the new reader in the appropriate per-CPU element of the * Counts the new reader in the appropriate per-CPU element of the
* srcu_struct. Must be called from process context. * srcu_struct.
* Returns an index that must be passed to the matching srcu_read_unlock(). * Returns an index that must be passed to the matching srcu_read_unlock().
*/ */
int __srcu_read_lock(struct srcu_struct *sp) int __srcu_read_lock(struct srcu_struct *sp)
@ -365,7 +365,7 @@ int __srcu_read_lock(struct srcu_struct *sp)
int idx; int idx;
idx = READ_ONCE(sp->srcu_idx) & 0x1; idx = READ_ONCE(sp->srcu_idx) & 0x1;
__this_cpu_inc(sp->sda->srcu_lock_count[idx]); this_cpu_inc(sp->sda->srcu_lock_count[idx]);
smp_mb(); /* B */ /* Avoid leaking the critical section. */ smp_mb(); /* B */ /* Avoid leaking the critical section. */
return idx; return idx;
} }
@ -375,7 +375,6 @@ EXPORT_SYMBOL_GPL(__srcu_read_lock);
* Removes the count for the old reader from the appropriate per-CPU * Removes the count for the old reader from the appropriate per-CPU
* element of the srcu_struct. Note that this may well be a different * element of the srcu_struct. Note that this may well be a different
* CPU than that which was incremented by the corresponding srcu_read_lock(). * CPU than that which was incremented by the corresponding srcu_read_lock().
* Must be called from process context.
*/ */
void __srcu_read_unlock(struct srcu_struct *sp, int idx) void __srcu_read_unlock(struct srcu_struct *sp, int idx)
{ {