Commit dbe1bdbb authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: handle signals for IO threads like a normal thread 



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.

Acked-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 10442994

fs/io-wq.c

+14 −6
Original line number Diff line number Diff line
@@ -16,7 +16,6 @@ 
#include <linux/rculist_nulls.h>

#include <linux/cpu.h>

#include <linux/tracehook.h>

#include <linux/freezer.h>



#include "../kernel/sched/sched.h"

#include "io-wq.h"
@@ -503,10 +502,15 @@ static int io_wqe_worker(void *data) 
		if (io_flush_signals())

			continue;

		ret = schedule_timeout(WORKER_IDLE_TIMEOUT);

		if (try_to_freeze() || ret)

		if (signal_pending(current)) {

			struct ksignal ksig;



			if (!get_signal(&ksig))

				continue;

		if (fatal_signal_pending(current))

			break;

		}

		if (ret)

			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))
@@ -714,9 +718,13 @@ static int io_wq_manager(void *data) 
		set_current_state(TASK_INTERRUPTIBLE);

		io_wq_check_workers(wq);

		schedule_timeout(HZ);

		try_to_freeze();

		if (fatal_signal_pending(current))

		if (signal_pending(current)) {

			struct ksignal ksig;



			if (!get_signal(&ksig))

				continue;

			set_bit(IO_WQ_BIT_EXIT, &wq->state);

		}

	} while (!test_bit(IO_WQ_BIT_EXIT, &wq->state));



	io_wq_check_workers(wq);

fs/io_uring.c

+6 −3
Original line number Diff line number Diff line
@@ -78,7 +78,6 @@ 
#include <linux/task_work.h>

#include <linux/pagemap.h>

#include <linux/io_uring.h>

#include <linux/freezer.h>



#define CREATE_TRACE_POINTS

#include <trace/events/io_uring.h>
@@ -6765,8 +6764,13 @@ static int io_sq_thread(void *data) 
			timeout = jiffies + sqd->sq_thread_idle;

			continue;

		}

		if (fatal_signal_pending(current))

		if (signal_pending(current)) {

			struct ksignal ksig;



			if (!get_signal(&ksig))

				continue;

			break;

		}

		sqt_spin = false;

		cap_entries = !list_is_singular(&sqd->ctx_list);

		list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
@@ -6809,7 +6813,6 @@ static int io_sq_thread(void *data) 


			mutex_unlock(&sqd->lock);

			schedule();

			try_to_freeze();

			mutex_lock(&sqd->lock);

			list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)

				io_ring_clear_wakeup_flag(ctx);