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Tue, 21 Apr 2026 17:12:16 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id yf1VKPCv52mlaQAAD6G6ig (envelope-from ); Tue, 21 Apr 2026 17:12:16 +0000 From: Gabriel Krisman Bertazi To: Jens Axboe Cc: io-uring@vger.kernel.org, stable@kernel.org Subject: Re: [PATCH 6/6] io_uring/register: fix ring resizing with mixed/large SQEs/CQEs In-Reply-To: <20260421135626.581917-7-axboe@kernel.dk> (Jens Axboe's message of "Tue, 21 Apr 2026 07:51:43 -0600") References: <20260421135626.581917-1-axboe@kernel.dk> <20260421135626.581917-7-axboe@kernel.dk> Date: Tue, 21 Apr 2026 13:12:10 -0400 Message-ID: <87tst4p79x.fsf@mailhost.krisman.be> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; FUZZY_RATELIMITED(0.00)[rspamd.com]; MIME_TRACE(0.00)[0:+]; TO_DN_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,suse.de:email,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,kernel.dk:email]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -4.51 X-Spam-Level: X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Queue-Id: 1E56A6A8E7 Jens Axboe writes: > The ring resizing only properly handles "normal" sized SQEs or CQEs, if > there are pending entries around a resize. This normally should not be > the case, but the code is supposed to handle this regardless. > > For the mixed SQE/CQE cases, the current copying works fine as they > are indexed in the same way. Each half is just copied separately. But > for fixed large SQEs and CQEs, the iteration and copy need to take that > into account. > > Cc: stable@kernel.org > Fixes: 79cfe9e59c2a ("io_uring/register: add IORING_REGISTER_RESIZE_RINGS") > Signed-off-by: Jens Axboe > --- > io_uring/register.c | 36 ++++++++++++++++++++++++++++-------- > 1 file changed, 28 insertions(+), 8 deletions(-) > > diff --git a/io_uring/register.c b/io_uring/register.c > index 24e593332d1a..dce5e2f9cf77 100644 > --- a/io_uring/register.c > +++ b/io_uring/register.c > @@ -599,10 +599,20 @@ static int io_register_resize_rings(struct io_ring_ctx *ctx, void __user *arg) > if (tail - old_head > p->sq_entries) > goto overflow; > for (i = old_head; i < tail; i++) { > - unsigned src_head = i & (ctx->sq_entries - 1); > - unsigned dst_head = i & (p->sq_entries - 1); > - > - n.sq_sqes[dst_head] = o.sq_sqes[src_head]; > + unsigned index, dst_mask, src_mask; > + size_t sq_size; > + > + index = i; > + sq_size = sizeof(struct io_uring_sqe); > + src_mask = ctx->sq_entries - 1; > + dst_mask = p->sq_entries - 1; > + if (ctx->flags & IORING_SETUP_SQE128) { > + index <<= 1; > + sq_size <<= 1; > + src_mask = (ctx->sq_entries << 1) - 1; > + dst_mask = (p->sq_entries << 1) - 1; > + } > + memcpy(&n.sq_sqes[index & dst_mask], &o.sq_sqes[index & src_mask], sq_size); > } > WRITE_ONCE(n.rings->sq.head, old_head); > WRITE_ONCE(n.rings->sq.tail, tail); > @@ -619,10 +629,20 @@ static int io_register_resize_rings(struct io_ring_ctx *ctx, void __user *arg) > goto out; > } > for (i = old_head; i < tail; i++) { > - unsigned src_head = i & (ctx->cq_entries - 1); > - unsigned dst_head = i & (p->cq_entries - 1); > - > - n.rings->cqes[dst_head] = o.rings->cqes[src_head]; > + unsigned index, dst_mask, src_mask; > + size_t cq_size; > + > + index = i; > + cq_size = sizeof(struct io_uring_cqe); > + src_mask = ctx->cq_entries - 1; > + dst_mask = p->cq_entries - 1; > + if (ctx->flags & IORING_SETUP_CQE32) { > + index <<= 1; > + cq_size <<= 1; > + src_mask = (ctx->cq_entries << 1) - 1; > + dst_mask = (p->cq_entries << 1) - 1; > + } > + memcpy(&n.rings->cqes[index & dst_mask], &o.rings->cqes[index & src_mask], cq_size); > } > WRITE_ONCE(n.rings->cq.head, old_head); > WRITE_ONCE(n.rings->cq.tail, tail); Reviewed-by: Gabriel Krisman Bertazi -- Gabriel Krisman Bertazi