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From: Jens Axboe <[email protected]>
To: [email protected]
Cc: [email protected], [email protected],
	[email protected], [email protected], [email protected],
	Jens Axboe <[email protected]>
Subject: [PATCH 1/8] io_uring: handle signals for IO threads like a normal thread
Date: Thu, 25 Mar 2021 18:39:24 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

We go through various hoops to disallow signals for the IO threads, but
there's really no reason why we cannot just allow them. The IO threads
never return to userspace like a normal thread, and hence don't go through
normal signal processing. Instead, just check for a pending signal as part
of the work loop, and call get_signal() to handle it for us if anything
is pending.

With that, we can support receiving signals, including special ones like
SIGSTOP.

Signed-off-by: Jens Axboe <[email protected]>
---
 fs/io-wq.c    | 21 +++++++++++++++++----
 fs/io_uring.c | 10 ++++++++--
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index b7c1fa932cb3..2dbdc552f3ba 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -505,8 +505,14 @@ static int io_wqe_worker(void *data)
 		ret = schedule_timeout(WORKER_IDLE_TIMEOUT);
 		if (try_to_freeze() || ret)
 			continue;
-		if (fatal_signal_pending(current))
-			break;
+		if (signal_pending(current)) {
+			struct ksignal ksig;
+
+			if (fatal_signal_pending(current))
+				break;
+			get_signal(&ksig);
+			continue;
+		}
 		/* timed out, exit unless we're the fixed worker */
 		if (test_bit(IO_WQ_BIT_EXIT, &wq->state) ||
 		    !(worker->flags & IO_WORKER_F_FIXED))
@@ -715,8 +721,15 @@ static int io_wq_manager(void *data)
 		io_wq_check_workers(wq);
 		schedule_timeout(HZ);
 		try_to_freeze();
-		if (fatal_signal_pending(current))
-			set_bit(IO_WQ_BIT_EXIT, &wq->state);
+		if (signal_pending(current)) {
+			struct ksignal ksig;
+
+			if (fatal_signal_pending(current))
+				set_bit(IO_WQ_BIT_EXIT, &wq->state);
+			else
+				get_signal(&ksig);
+			continue;
+		}
 	} while (!test_bit(IO_WQ_BIT_EXIT, &wq->state));
 
 	io_wq_check_workers(wq);
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 54ea561db4a5..3a9d021db328 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6765,8 +6765,14 @@ static int io_sq_thread(void *data)
 			timeout = jiffies + sqd->sq_thread_idle;
 			continue;
 		}
-		if (fatal_signal_pending(current))
-			break;
+		if (signal_pending(current)) {
+			struct ksignal ksig;
+
+			if (fatal_signal_pending(current))
+				break;
+			get_signal(&ksig);
+			continue;
+		}
 		sqt_spin = false;
 		cap_entries = !list_is_singular(&sqd->ctx_list);
 		list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
-- 
2.31.0


  reply	other threads:[~2021-03-26  0:41 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-26  0:39 [PATCH 0/6] Allow signals for IO threads Jens Axboe
2021-03-26  0:39 ` Jens Axboe [this message]
2021-03-26  0:39 ` [PATCH 2/8] kernel: unmask SIGSTOP " Jens Axboe
2021-03-26 13:48   ` Oleg Nesterov
2021-03-26 15:01     ` Jens Axboe
2021-03-26 15:23       ` Stefan Metzmacher
2021-03-26 15:29         ` Jens Axboe
2021-03-26 18:01           ` Stefan Metzmacher
2021-03-26 18:59             ` Jens Axboe
2021-04-01 14:53             ` Stefan Metzmacher
2021-03-26  0:39 ` [PATCH 3/8] Revert "signal: don't allow sending any signals to PF_IO_WORKER threads" Jens Axboe
2021-03-26  0:39 ` [PATCH 4/8] Revert "kernel: treat PF_IO_WORKER like PF_KTHREAD for ptrace/signals" Jens Axboe
2021-03-26  0:39 ` [PATCH 5/8] Revert "kernel: freezer should treat PF_IO_WORKER like PF_KTHREAD for freezing" Jens Axboe
2021-03-26  0:39 ` [PATCH 6/8] Revert "signal: don't allow STOP on PF_IO_WORKER threads" Jens Axboe
     [not found] ` <[email protected]>
2021-03-26 12:56   ` [PATCH 0/6] Allow signals for IO threads Jens Axboe
2021-03-26 13:31     ` Stefan Metzmacher
2021-03-26 13:54       ` Jens Axboe
2021-03-26 13:59         ` Jens Axboe
2021-03-26 14:38           ` Jens Axboe
2021-03-26 14:43             ` Stefan Metzmacher
2021-03-26 14:45               ` Stefan Metzmacher
2021-03-26 14:53                 ` Jens Axboe
2021-03-26 14:55                   ` Jens Axboe
2021-03-26 15:08                     ` Stefan Metzmacher
2021-03-26 15:10                       ` Jens Axboe
2021-03-26 15:11                         ` Stefan Metzmacher
2021-03-26 15:12                           ` Jens Axboe
2021-03-26 15:04                   ` Stefan Metzmacher
2021-03-26 15:09                     ` Jens Axboe
2021-03-26 14:50               ` Jens Axboe
2021-03-27  1:46       ` Stefan Metzmacher
2021-03-27 16:41         ` Jens Axboe
2021-04-01 14:58         ` Stefan Metzmacher
2021-04-01 15:39           ` Linus Torvalds
2021-04-01 16:00             ` Stefan Metzmacher
2021-04-01 16:24               ` Linus Torvalds
2021-04-03  0:48                 ` Stefan Metzmacher

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