From 6aa7de059173a986114ac43b8f50b297a86f09a8 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 23 Oct 2017 14:07:29 -0700 Subject: locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE() Please do not apply this to mainline directly, instead please re-run the coccinelle script shown below and apply its output. For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't harmful, and changing them results in churn. However, for some features, the read/write distinction is critical to correct operation. To distinguish these cases, separate read/write accessors must be used. This patch migrates (most) remaining ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following coccinelle script: ---- // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and // WRITE_ONCE() // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland Signed-off-by: Paul E. McKenney Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar --- drivers/md/dm-stats.c | 36 ++++++++++++++++++------------------ 1 file changed, 18 insertions(+), 18 deletions(-) (limited to 'drivers/md/dm-stats.c') diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c index 6028d8247f58..a1a5eec783cc 100644 --- a/drivers/md/dm-stats.c +++ b/drivers/md/dm-stats.c @@ -431,7 +431,7 @@ do_sync_free: synchronize_rcu_expedited(); dm_stat_free(&s->rcu_head); } else { - ACCESS_ONCE(dm_stat_need_rcu_barrier) = 1; + WRITE_ONCE(dm_stat_need_rcu_barrier, 1); call_rcu(&s->rcu_head, dm_stat_free); } return 0; @@ -639,12 +639,12 @@ void dm_stats_account_io(struct dm_stats *stats, unsigned long bi_rw, */ last = raw_cpu_ptr(stats->last); stats_aux->merged = - (bi_sector == (ACCESS_ONCE(last->last_sector) && + (bi_sector == (READ_ONCE(last->last_sector) && ((bi_rw == WRITE) == - (ACCESS_ONCE(last->last_rw) == WRITE)) + (READ_ONCE(last->last_rw) == WRITE)) )); - ACCESS_ONCE(last->last_sector) = end_sector; - ACCESS_ONCE(last->last_rw) = bi_rw; + WRITE_ONCE(last->last_sector, end_sector); + WRITE_ONCE(last->last_rw, bi_rw); } rcu_read_lock(); @@ -693,22 +693,22 @@ static void __dm_stat_init_temporary_percpu_totals(struct dm_stat_shared *shared for_each_possible_cpu(cpu) { p = &s->stat_percpu[cpu][x]; - shared->tmp.sectors[READ] += ACCESS_ONCE(p->sectors[READ]); - shared->tmp.sectors[WRITE] += ACCESS_ONCE(p->sectors[WRITE]); - shared->tmp.ios[READ] += ACCESS_ONCE(p->ios[READ]); - shared->tmp.ios[WRITE] += ACCESS_ONCE(p->ios[WRITE]); - shared->tmp.merges[READ] += ACCESS_ONCE(p->merges[READ]); - shared->tmp.merges[WRITE] += ACCESS_ONCE(p->merges[WRITE]); - shared->tmp.ticks[READ] += ACCESS_ONCE(p->ticks[READ]); - shared->tmp.ticks[WRITE] += ACCESS_ONCE(p->ticks[WRITE]); - shared->tmp.io_ticks[READ] += ACCESS_ONCE(p->io_ticks[READ]); - shared->tmp.io_ticks[WRITE] += ACCESS_ONCE(p->io_ticks[WRITE]); - shared->tmp.io_ticks_total += ACCESS_ONCE(p->io_ticks_total); - shared->tmp.time_in_queue += ACCESS_ONCE(p->time_in_queue); + shared->tmp.sectors[READ] += READ_ONCE(p->sectors[READ]); + shared->tmp.sectors[WRITE] += READ_ONCE(p->sectors[WRITE]); + shared->tmp.ios[READ] += READ_ONCE(p->ios[READ]); + shared->tmp.ios[WRITE] += READ_ONCE(p->ios[WRITE]); + shared->tmp.merges[READ] += READ_ONCE(p->merges[READ]); + shared->tmp.merges[WRITE] += READ_ONCE(p->merges[WRITE]); + shared->tmp.ticks[READ] += READ_ONCE(p->ticks[READ]); + shared->tmp.ticks[WRITE] += READ_ONCE(p->ticks[WRITE]); + shared->tmp.io_ticks[READ] += READ_ONCE(p->io_ticks[READ]); + shared->tmp.io_ticks[WRITE] += READ_ONCE(p->io_ticks[WRITE]); + shared->tmp.io_ticks_total += READ_ONCE(p->io_ticks_total); + shared->tmp.time_in_queue += READ_ONCE(p->time_in_queue); if (s->n_histogram_entries) { unsigned i; for (i = 0; i < s->n_histogram_entries + 1; i++) - shared->tmp.histogram[i] += ACCESS_ONCE(p->histogram[i]); + shared->tmp.histogram[i] += READ_ONCE(p->histogram[i]); } } } -- cgit v1.2.1