Messages in this thread Patch in this message | | | Date | Sun, 10 Jul 2022 11:25:47 +0900 | Subject | [PATCH v2 4/4] PM: hibernate: don't set PF_FREEZER_SKIP flag when manipulating /dev/snapshot | From | Tetsuo Handa <> |
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Since khungtaskd skips threads with PF_FREEZER_SKIP flag set, currently we can't report unbounded uninterruptible sleep when something went wrong while manipulating /dev/snapshot interface.
Let's change snapshot_{open,read,write}() to use mutex_lock_killable() and change snapshot_release() to use mutex_lock(), so that khungtaskd can report unbounded uninterruptible sleep, by not setting PF_FREEZER_SKIP flag.
Since /dev/snapshot is exclusive due to hibernate_acquire(), we could choose mutex_trylock() for snapshot_{open,read,write}() as with snapshot_ioctl(). But until we confirm that this patch does not break something, let's stay mutex_lock_killable().
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Len Brown <len.brown@intel.com> Cc: Pavel Machek <pavel@ucw.cz> --- This patch is only compile tested. Need to review if somewhere depends on PF_FREEZER_SKIP flag being set.
kernel/power/user.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/kernel/power/user.c b/kernel/power/user.c index 32dd5a855e8c..9936efa07022 100644 --- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -68,7 +68,8 @@ static int snapshot_open(struct inode *inode, struct file *filp) break; } - lock_system_sleep(); + if (mutex_lock_killable(&system_transition_mutex)) + return -EINTR; if (!hibernate_acquire()) { error = -EBUSY; @@ -102,7 +103,7 @@ static int snapshot_open(struct inode *inode, struct file *filp) data->dev = 0; Unlock: - unlock_system_sleep(); + mutex_unlock(&system_transition_mutex); return error; } @@ -111,7 +112,7 @@ static int snapshot_release(struct inode *inode, struct file *filp) { struct snapshot_data *data; - lock_system_sleep(); + mutex_lock(&system_transition_mutex); swsusp_free(); data = filp->private_data; @@ -128,7 +129,7 @@ static int snapshot_release(struct inode *inode, struct file *filp) PM_POST_HIBERNATION : PM_POST_RESTORE); hibernate_release(); - unlock_system_sleep(); + mutex_unlock(&system_transition_mutex); return 0; } @@ -140,7 +141,8 @@ static ssize_t snapshot_read(struct file *filp, char __user *buf, ssize_t res; loff_t pg_offp = *offp & ~PAGE_MASK; - lock_system_sleep(); + if (mutex_lock_killable(&system_transition_mutex)) + return -EINTR; data = filp->private_data; if (!data->ready) { @@ -161,7 +163,7 @@ static ssize_t snapshot_read(struct file *filp, char __user *buf, *offp += res; Unlock: - unlock_system_sleep(); + mutex_unlock(&system_transition_mutex); return res; } @@ -173,7 +175,8 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf, ssize_t res; loff_t pg_offp = *offp & ~PAGE_MASK; - lock_system_sleep(); + if (mutex_lock_killable(&system_transition_mutex)) + return -EINTR; data = filp->private_data; @@ -195,7 +198,7 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf, if (res > 0) *offp += res; unlock: - unlock_system_sleep(); + mutex_unlock(&system_transition_mutex); return res; } -- 2.18.4
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