When the number of available events in the ring buffer is calculated,
the avail calculation is incorrect when head == tail. This is harmless
in aio_read_events_ring(), but in free_ioctx() leads to the subsequent
WARN_ON(atomic_read(&ctx->reqs_available) > ctx->nr). Correct this.
Signed-off-by: Benjamin LaHaise <bcrl@xxxxxxxxx>
---
fs/aio.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 24ba228..dc52b0c 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -337,7 +337,8 @@ static void free_ioctx(struct kioctx *ctx)
while (atomic_read(&ctx->reqs_available) < ctx->nr) {
wait_event(ctx->wait, head != ctx->shadow_tail);
- avail = (head < ctx->shadow_tail ? ctx->shadow_tail : ctx->nr) - head;
+ avail = (head <= ctx->shadow_tail ?
+ ctx->shadow_tail : ctx->nr) - head;
atomic_add(avail, &ctx->reqs_available);
head += avail;
@@ -884,7 +885,7 @@ static long aio_read_events_ring(struct kioctx *ctx,
goto out;
while (ret < nr) {
- long avail = (head < ctx->shadow_tail
+ long avail = (head <= ctx->shadow_tail
? ctx->shadow_tail : ctx->nr) - head;
struct io_event *ev;
struct page *page;
--
1.7.4.1
--
"Thought is the essence of where you are now."
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