Commit a566c556 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe
Browse files

io_uring: remove dependency on ring->sq/cq_entries 



We have numbers of {sq,cq} entries cached in ctx, don't look up them in
user-shared rings as 1) it may fetch additional cacheline 2) user may
change it and so it's always error prone.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/745d31bc2da41283ddd0489ef784af5c8d6310e9.1621201931.git.asml.silence@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent b13a8918

fs/io_uring.c

+3 −4
Original line number Diff line number Diff line
@@ -1356,7 +1356,7 @@ static inline bool io_sqring_full(struct io_ring_ctx *ctx) 
{

	struct io_rings *r = ctx->rings;



	return READ_ONCE(r->sq.tail) - ctx->cached_sq_head == r->sq_ring_entries;

	return READ_ONCE(r->sq.tail) - ctx->cached_sq_head == ctx->sq_entries;

}



static inline unsigned int __io_cqring_events(struct io_ring_ctx *ctx)
@@ -1374,7 +1374,7 @@ static inline struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx) 
	 * control dependency is enough as we're using WRITE_ONCE to

	 * fill the cq entry

	 */

	if (__io_cqring_events(ctx) == rings->cq_ring_entries)

	if (__io_cqring_events(ctx) == ctx->cq_entries)

		return NULL;



	tail = ctx->cached_cq_tail++;
@@ -1427,11 +1427,10 @@ static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx) 
/* Returns true if there are no backlogged entries after the flush */

static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force)

{

	struct io_rings *rings = ctx->rings;

	unsigned long flags;

	bool all_flushed, posted;



	if (!force && __io_cqring_events(ctx) == rings->cq_ring_entries)

	if (!force && __io_cqring_events(ctx) == ctx->cq_entries)

		return false;



	posted = false;