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From: Pavel Begunkov <asml.silence@gmail.com>
To: io-uring@vger.kernel.org
Cc: linux-block@vger.kernel.org,
Jens Axboe <axboe@kernel.dk>,
asml.silence@gmail.com,
Kanchan Joshi <joshi.k@samsung.com>,
Ming Lei <ming.lei@redhat.com>
Subject: [PATCH v2 03/14] io_uring/cmd: make io_uring_cmd_done irq safe
Date: Mon, 18 Mar 2024 00:41:48 +0000
Message-ID: <faeec0d1e7c740a582f51f80626f61c745ed9a52.1710720150.git.asml.silence@gmail.com>
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io_uring_cmd_done() is called from the irq context and is considered to
be irq safe, however that's not the case if the driver requires
cancellations because io_uring_cmd_del_cancelable() could try to take
the uring_lock mutex.
Clean up the confusion, by deferring cancellation handling to
locked task_work if we came into io_uring_cmd_done() from iowq
or other IO_URING_F_UNLOCKED path.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
io_uring/uring_cmd.c | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index ec38a8d4836d..9590081feb2d 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -14,19 +14,18 @@
#include "rsrc.h"
#include "uring_cmd.h"
-static void io_uring_cmd_del_cancelable(struct io_uring_cmd *cmd,
- unsigned int issue_flags)
+static void io_uring_cmd_del_cancelable(struct io_uring_cmd *cmd)
{
struct io_kiocb *req = cmd_to_io_kiocb(cmd);
struct io_ring_ctx *ctx = req->ctx;
+ lockdep_assert_held(&ctx->uring_lock);
+
if (!(cmd->flags & IORING_URING_CMD_CANCELABLE))
return;
cmd->flags &= ~IORING_URING_CMD_CANCELABLE;
- io_ring_submit_lock(ctx, issue_flags);
hlist_del(&req->hash_node);
- io_ring_submit_unlock(ctx, issue_flags);
}
/*
@@ -44,6 +43,9 @@ void io_uring_cmd_mark_cancelable(struct io_uring_cmd *cmd,
struct io_kiocb *req = cmd_to_io_kiocb(cmd);
struct io_ring_ctx *ctx = req->ctx;
+ if (WARN_ON_ONCE(ctx->flags & IORING_SETUP_IOPOLL))
+ return;
+
if (!(cmd->flags & IORING_URING_CMD_CANCELABLE)) {
cmd->flags |= IORING_URING_CMD_CANCELABLE;
io_ring_submit_lock(ctx, issue_flags);
@@ -84,6 +86,15 @@ static inline void io_req_set_cqe32_extra(struct io_kiocb *req,
req->big_cqe.extra2 = extra2;
}
+static void io_req_cmd_task_complete(struct io_kiocb *req, struct io_tw_state *ts)
+{
+ struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd);
+
+ io_tw_lock(req->ctx, ts);
+ io_uring_cmd_del_cancelable(ioucmd);
+ io_req_task_complete(req, ts);
+}
+
/*
* Called by consumers of io_uring_cmd, if they originally returned
* -EIOCBQUEUED upon receiving the command.
@@ -93,8 +104,6 @@ void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2,
{
struct io_kiocb *req = cmd_to_io_kiocb(ioucmd);
- io_uring_cmd_del_cancelable(ioucmd, issue_flags);
-
if (ret < 0)
req_set_fail(req);
@@ -107,9 +116,10 @@ void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret, ssize_t res2,
} else if (issue_flags & IO_URING_F_COMPLETE_DEFER) {
if (WARN_ON_ONCE(issue_flags & IO_URING_F_UNLOCKED))
return;
+ io_uring_cmd_del_cancelable(ioucmd);
io_req_complete_defer(req);
} else {
- req->io_task_work.func = io_req_task_complete;
+ req->io_task_work.func = io_req_cmd_task_complete;
io_req_task_work_add(req);
}
}
--
2.44.0