linux-kernel - [PATCH 04/23] io_uring: deduce cq_mask from cq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <f5fc827237c2d339d3fdae8a0588763ba3e1d0f1.1621424513.git.asml.silence@gmail.com>
Date:   Wed, 19 May 2021 15:13:15 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     io-uring@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Jens Axboe <axboe@...nel.dk>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Horst Schirmeier <horst.schirmeier@...dortmund.de>,
        "Franz-B . Tuneke" <franz-bernhard.tuneke@...dortmund.de>,
        Christian Dietrich <stettberger@...ucode.de>
Subject: [PATCH 04/23] 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@...il.com>
---
 fs/io_uring.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 15dc5dad1f7d..067c89e63fea 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -361,7 +361,6 @@ 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;
@@ -407,7 +406,6 @@ 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;
@@ -1363,7 +1361,7 @@ 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
@@ -1374,7 +1372,7 @@ 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)
@@ -6677,7 +6675,7 @@ 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:
@@ -6687,7 +6685,7 @@ 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];
 
@@ -9493,8 +9491,6 @@ 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) {
-- 
2.31.1