From: Oleg Nesterov <oleg@redhat.com>
To: Al Viro <viro@ZenIV.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Benjamin LaHaise <bcrl@kvack.org>, Jeff Moyer <jmoyer@redhat.com>
Cc: linux-aio@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3 2/3] aio: make aio_ring->dead boolean
Date: Thu, 18 Jun 2015 19:52:09 +0200 [thread overview]
Message-ID: <20150618175209.GA10060@redhat.com> (raw)
In-Reply-To: <20150618175143.GA10033@redhat.com>
"atomic_t dead" makes no sense. atomic_read() is the plain LOAD,
it doesn't have some "additional" synchronization with xchg().
And now that kill_ioctx() sets "dead" under mm->ioctx_lock we do
not even need xchg().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
---
fs/aio.c | 9 +++++----
1 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 893d300..d63a889 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -84,7 +84,7 @@ struct ctx_rq_wait {
struct kioctx {
struct percpu_ref users;
- atomic_t dead;
+ bool dead;
struct percpu_ref reqs;
@@ -765,7 +765,7 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
err_cleanup:
aio_nr_sub(ctx->max_reqs);
err_ctx:
- atomic_set(&ctx->dead, 1);
+ ctx->dead = true; /* unneeded */
if (ctx->mmap_size)
vm_munmap(ctx->mmap_base, ctx->mmap_size);
aio_free_ring(ctx);
@@ -790,11 +790,12 @@ static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
struct kioctx_table *table;
spin_lock(&mm->ioctx_lock);
- if (atomic_xchg(&ctx->dead, 1)) {
+ if (unlikely(ctx->dead)) {
spin_unlock(&mm->ioctx_lock);
return -EINVAL;
}
+ ctx->dead = true;
table = rcu_dereference_raw(mm->ioctx_table);
WARN_ON(ctx != table->table[ctx->id]);
table->table[ctx->id] = NULL;
@@ -1236,7 +1237,7 @@ static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
if (ret > 0)
*i += ret;
- if (unlikely(atomic_read(&ctx->dead)))
+ if (unlikely(ctx->dead))
ret = -EINVAL;
if (!*i)
--
1.5.5.1
next prev parent reply other threads:[~2015-06-18 17:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-18 17:51 [PATCH v3 0/3] aio: ctx->dead cleanups Oleg Nesterov
2015-06-18 17:52 ` [PATCH v3 1/3] aio_ring_remap: kill the bogus ctx->dead check Oleg Nesterov
2015-06-18 17:52 ` Oleg Nesterov [this message]
2015-06-18 18:02 ` [PATCH v3 2/3] aio: make aio_ring->dead boolean Jeff Moyer
2015-06-18 18:27 ` Oleg Nesterov
2015-06-18 17:52 ` [PATCH v3 3/3] aio_free_ring: don't do page_count(NULL) Oleg Nesterov
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