From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Subject: [PATCH 2/4] io_uring: patch up IOPOLL overflow_flush sync
Date: Sat, 2 Jan 2021 16:06:52 +0000 [thread overview]
Message-ID: <716bb8006495b33f11cb2f252ed5506d86f9f85c.1609600704.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>
IOPOLL skips completion locking but keeps it under uring_lock, thus
io_cqring_overflow_flush() and so io_cqring_events() need extra care.
Add extra conditional locking around them.
Signed-off-by: Pavel Begunkov <[email protected]>
---
fs/io_uring.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 00dd85acd039..a4deef746bc3 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2312,7 +2312,8 @@ static void io_double_put_req(struct io_kiocb *req)
io_free_req(req);
}
-static unsigned io_cqring_events(struct io_ring_ctx *ctx, bool noflush)
+static unsigned io_cqring_events(struct io_ring_ctx *ctx, bool noflush,
+ bool iopoll_lock)
{
if (test_bit(0, &ctx->cq_check_overflow)) {
/*
@@ -2323,7 +2324,15 @@ static unsigned io_cqring_events(struct io_ring_ctx *ctx, bool noflush)
if (noflush)
return -1U;
+ /*
+ * iopoll doesn't care about ctx->completion_lock but uses
+ * ctx->uring_lock
+ */
+ if (iopoll_lock)
+ mutex_lock(&ctx->uring_lock);
io_cqring_overflow_flush(ctx, false, NULL, NULL);
+ if (iopoll_lock)
+ mutex_unlock(&ctx->uring_lock);
}
/* See comment at the top of this file */
@@ -2550,7 +2559,7 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
* If we do, we can potentially be spinning for commands that
* already triggered a CQE (eg in error).
*/
- if (io_cqring_events(ctx, false))
+ if (io_cqring_events(ctx, false, false))
break;
/*
@@ -7097,7 +7106,7 @@ static inline bool io_should_wake(struct io_wait_queue *iowq, bool noflush)
* started waiting. For timeouts, we always want to return to userspace,
* regardless of event count.
*/
- return io_cqring_events(ctx, noflush) >= iowq->to_wait ||
+ return io_cqring_events(ctx, noflush, false) >= iowq->to_wait ||
atomic_read(&ctx->cq_timeouts) != iowq->nr_timeouts;
}
@@ -7142,13 +7151,14 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
.ctx = ctx,
.to_wait = min_events,
};
+ bool iopoll = ctx->flags & IORING_SETUP_IOPOLL;
struct io_rings *rings = ctx->rings;
struct timespec64 ts;
signed long timeout = 0;
int ret = 0;
do {
- if (io_cqring_events(ctx, false) >= min_events)
+ if (io_cqring_events(ctx, false, iopoll) >= min_events)
return 0;
if (!io_run_task_work())
break;
@@ -7184,7 +7194,8 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
continue;
else if (ret < 0)
break;
- if (io_should_wake(&iowq, false))
+ /* iopoll ignores completion_lock, so not safe to flush */
+ if (io_should_wake(&iowq, iopoll))
break;
if (uts) {
timeout = schedule_timeout(timeout);
@@ -8623,7 +8634,7 @@ static __poll_t io_uring_poll(struct file *file, poll_table *wait)
smp_rmb();
if (!io_sqring_full(ctx))
mask |= EPOLLOUT | EPOLLWRNORM;
- if (io_cqring_events(ctx, false))
+ if (io_cqring_events(ctx, false, ctx->flags & IORING_SETUP_IOPOLL))
mask |= EPOLLIN | EPOLLRDNORM;
return mask;
--
2.24.0
next prev parent reply other threads:[~2021-01-02 16:12 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-02 16:06 [PATCH 0/4] bunch of random fixes Pavel Begunkov
2021-01-02 16:06 ` [PATCH 1/4] io_uring: dont kill fasync under completion_lock Pavel Begunkov
2021-01-03 11:58 ` Pavel Begunkov
2021-01-02 16:06 ` Pavel Begunkov [this message]
2021-01-03 15:12 ` [PATCH 2/4] io_uring: patch up IOPOLL overflow_flush sync Jens Axboe
2021-01-03 16:29 ` Pavel Begunkov
2021-01-03 22:05 ` Jens Axboe
2021-01-02 16:06 ` [PATCH 3/4] io_uring: drop file refs after task cancel Pavel Begunkov
2021-01-02 16:06 ` [PATCH 4/4] io_uring: cancel more aggressively in exit_work Pavel Begunkov
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