The patch titled
srcu-3: improved comment and code-style improvements from Joe Perches
has been removed from the -mm tree. Its filename is
srcu-3-rcu-variant-permitting-read-side-blocking-fix.patch
This patch was dropped because it was folded into srcu-3-rcu-variant-permitting-read-side-blocking.patch
------------------------------------------------------
Subject: srcu-3: improved comment and code-style improvements from Joe Perches
From: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
An improved comment for synchronize_srcu() and fixes for code-style bugs
pointed out by off-list by Joe Perches.
Cc: Joe Perches <joe@xxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/srcu.c | 14 +++++++-------
1 files changed, 7 insertions(+), 7 deletions(-)
diff -puN kernel/srcu.c~srcu-3-rcu-variant-permitting-read-side-blocking-fix kernel/srcu.c
--- a/kernel/srcu.c~srcu-3-rcu-variant-permitting-read-side-blocking-fix
+++ a/kernel/srcu.c
@@ -62,7 +62,7 @@ static int srcu_readers_active_idx(struc
sum = 0;
for_each_possible_cpu(cpu)
sum += per_cpu_ptr(sp->per_cpu_ref, cpu)->c[idx];
- return (sum);
+ return sum;
}
/**
@@ -144,11 +144,15 @@ void srcu_read_unlock(struct srcu_struct
* As with classic RCU, the updater must use some separate means of
* synchronizing concurrent updates. Can block; must be called from
* process context.
+ *
+ * Note that it is illegal to call synchornize_srcu() from the corresponding
+ * SRCU read-side critical section; doing so will result in deadlock.
+ * However, it is perfectly legal to call synchronize_srcu() on one
+ * srcu_struct from some other srcu_struct's read-side critical section.
*/
void synchronize_srcu(struct srcu_struct *sp)
{
int idx;
- int sum;
idx = sp->completed;
mutex_lock(&sp->mutex);
@@ -195,12 +199,8 @@ void synchronize_srcu(struct srcu_struct
* will have finished executing.
*/
- for (;;) {
- sum = srcu_readers_active_idx(sp, idx);
- if (sum == 0)
- break;
+ while (srcu_readers_active_idx(sp, idx))
schedule_timeout_interruptible(1);
- }
synchronize_sched(); /* Force memory barrier on all CPUs. */
_
Patches currently in -mm which might be from paulmck@xxxxxxxxxx are
origin.patch
srcu-3-rcu-variant-permitting-read-side-blocking.patch
srcu-3-rcu-variant-permitting-read-side-blocking-fix.patch
srcu-3-rcu-variant-permitting-read-side-blocking-srcu-add-lock-annotations.patch
srcu-3-rcu-variant-permitting-read-side-blocking-comments.patch
srcu-3-add-srcu-operations-to-rcutorture.patch
srcu-3-add-srcu-operations-to-rcutorture-fix.patch
add-srcu-based-notifier-chains.patch
add-srcu-based-notifier-chains-cleanup.patch
srcu-report-out-of-memory-errors.patch
srcu-report-out-of-memory-errors-fixlet.patch
cpufreq-make-the-transition_notifier-chain-use-srcu.patch
rcu-add-module_author-to-rcutorture-module.patch
rcu-mention-rcu_bh-in-description-of-rcutortures.patch
rcu-avoid-kthread_stop-on-invalid-pointer-if-rcutorture.patch
rcu-fix-sign-bug-making-rcu_random-always-return-the-same.patch
rcu-add-fake-writers-to-rcutorture.patch
rcu-add-fake-writers-to-rcutorture-tidy.patch
rcu-refactor-srcu_torture_deferred_free-to-work-for.patch
rcu-add-rcu_sync-torture-type-to-rcutorture.patch
rcu-add-rcu_bh_sync-torture-type-to-rcutorture.patch
rcu-add-sched-torture-type-to-rcutorture.patch
rcu-simplify-improve-batch-tuning.patch
rcu-credits-and-maintainers.patch
-
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