io_uring: deduce cq_mask from cq_entries

No need to cache cq_mask, it's exactly cq_entries - 1, so just deduce
it to not carry it around.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d439efad0503c8398451dae075e68a04362fbc8d.1621201931.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 169e951..a35a8dc 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -362,7 +362,6 @@ struct io_ring_ctx {
                u32                     *sq_array;
                unsigned                cached_sq_head;
                unsigned                sq_entries;
-               unsigned                sq_mask;
                unsigned                sq_thread_idle;
                unsigned                cached_sq_dropped;
                unsigned                cached_cq_overflow;
@@ -408,7 +407,6 @@ struct io_ring_ctx {
        struct {
                unsigned                cached_cq_tail;
                unsigned                cq_entries;
-               unsigned                cq_mask;
                atomic_t                cq_timeouts;
                unsigned                cq_last_tm_flush;
                unsigned                cq_extra;
@@ -1367,7 +1365,7 @@ static inline unsigned int __io_cqring_events(struct io_ring_ctx *ctx)
 static inline struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx)
 {
        struct io_rings *rings = ctx->rings;
-       unsigned tail;
+       unsigned tail, mask = ctx->cq_entries - 1;
 
        /*
         * writes to the cq entry need to come after reading head; the
@@ -1378,7 +1376,7 @@ static inline struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx)
                return NULL;
 
        tail = ctx->cached_cq_tail++;
-       return &rings->cqes[tail & ctx->cq_mask];
+       return &rings->cqes[tail & mask];
 }
 
 static inline bool io_should_trigger_evfd(struct io_ring_ctx *ctx)
@@ -6680,7 +6678,7 @@ static void io_commit_sqring(struct io_ring_ctx *ctx)
 static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
 {
        u32 *sq_array = ctx->sq_array;
-       unsigned head;
+       unsigned head, mask = ctx->sq_entries - 1;
 
        /*
         * The cached sq head (or cq tail) serves two purposes:
@@ -6690,7 +6688,7 @@ static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
         * 2) allows the kernel side to track the head on its own, even
         *    though the application is the one updating it.
         */
-       head = READ_ONCE(sq_array[ctx->cached_sq_head++ & ctx->sq_mask]);
+       head = READ_ONCE(sq_array[ctx->cached_sq_head++ & mask]);
        if (likely(head < ctx->sq_entries))
                return &ctx->sq_sqes[head];
 
@@ -9512,8 +9510,6 @@ static int io_allocate_scq_urings(struct io_ring_ctx *ctx,
        rings->cq_ring_mask = p->cq_entries - 1;
        rings->sq_ring_entries = p->sq_entries;
        rings->cq_ring_entries = p->cq_entries;
-       ctx->sq_mask = rings->sq_ring_mask;
-       ctx->cq_mask = rings->cq_ring_mask;
 
        size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
        if (size == SIZE_MAX) {