diff options
| author | Brian Norris <briannorris@chromium.org> | 2016-08-08 17:19:38 -0700 |
|---|---|---|
| committer | Jonathan Cameron <jic23@kernel.org> | 2016-08-21 16:22:44 +0100 |
| commit | fcf68f3c0bb2a541aa47a2a38b8939edf84fd529 (patch) | |
| tree | d7e6465c8956fd435ad1e1c394afa0967da67456 /drivers/iio | |
| parent | 522caebb2c3684f4a1d154526fb5e33f1381e92a (diff) | |
| download | linux-fcf68f3c0bb2a541aa47a2a38b8939edf84fd529.tar.bz2 | |
iio: fix sched WARNING "do not call blocking ops when !TASK_RUNNING"
When using CONFIG_DEBUG_ATOMIC_SLEEP, the scheduler nicely points out
that we're calling sleeping primitives within the wait_event loop, which
means we might clobber the task state:
[ 10.831289] do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffc00026b610>]
[ 10.845531] ------------[ cut here ]------------
[ 10.850161] WARNING: at kernel/sched/core.c:7630
...
[ 12.164333] ---[ end trace 45409966a9a76438 ]---
[ 12.168942] Call trace:
[ 12.171391] [<ffffffc00024ed44>] __might_sleep+0x64/0x90
[ 12.176699] [<ffffffc000954774>] mutex_lock_nested+0x50/0x3fc
[ 12.182440] [<ffffffc0007b9424>] iio_kfifo_buf_data_available+0x28/0x4c
[ 12.189043] [<ffffffc0007b76ac>] iio_buffer_ready+0x60/0xe0
[ 12.194608] [<ffffffc0007b7834>] iio_buffer_read_first_n_outer+0x108/0x1a8
[ 12.201474] [<ffffffc000370d48>] __vfs_read+0x58/0x114
[ 12.206606] [<ffffffc000371740>] vfs_read+0x94/0x118
[ 12.211564] [<ffffffc0003720f8>] SyS_read+0x64/0xb4
[ 12.216436] [<ffffffc000203cb4>] el0_svc_naked+0x24/0x28
To avoid this, we should (a la https://lwn.net/Articles/628628/) use the
wait_woken() function, which avoids the nested sleeping while still
handling races between waiting / wake-events.
Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: <Stable@vger.kernel.org> # 3.19+ for introduction of wake_woken
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'drivers/iio')
| -rw-r--r-- | drivers/iio/industrialio-buffer.c | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c index 90462fcf5436..49bf9c59f117 100644 --- a/drivers/iio/industrialio-buffer.c +++ b/drivers/iio/industrialio-buffer.c @@ -107,6 +107,7 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf, { struct iio_dev *indio_dev = filp->private_data; struct iio_buffer *rb = indio_dev->buffer; + DEFINE_WAIT_FUNC(wait, woken_wake_function); size_t datum_size; size_t to_wait; int ret; @@ -131,19 +132,29 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf, else to_wait = min_t(size_t, n / datum_size, rb->watermark); + add_wait_queue(&rb->pollq, &wait); do { - ret = wait_event_interruptible(rb->pollq, - iio_buffer_ready(indio_dev, rb, to_wait, n / datum_size)); - if (ret) - return ret; + if (!indio_dev->info) { + ret = -ENODEV; + break; + } - if (!indio_dev->info) - return -ENODEV; + if (!iio_buffer_ready(indio_dev, rb, to_wait, n / datum_size)) { + if (signal_pending(current)) { + ret = -ERESTARTSYS; + break; + } + + wait_woken(&wait, TASK_INTERRUPTIBLE, + MAX_SCHEDULE_TIMEOUT); + continue; + } ret = rb->access->read_first_n(rb, n, buf); if (ret == 0 && (filp->f_flags & O_NONBLOCK)) ret = -EAGAIN; } while (ret == 0); + remove_wait_queue(&rb->pollq, &wait); return ret; } |