| Message ID | 399e486c-6540-db27-76aa-7a271b061f76@tasossah.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | floppy: Fix hang in watchdog when disk is ejected | expand |
Hi, On 9/3/21 09:47, Tasos Sahanidis wrote: > When the watchdog detects a disk change, it calls cancel_activity(), > which in turn tries to cancel the fd_timer delayed work. > > In the above scenario, fd_timer_fn is set to fd_watchdog(), meaning > it is trying to cancel its own work. > This results in a hang as cancel_delayed_work_sync() is waiting for the > watchdog (itself) to return, which never happens. > > This can be reproduced relatively consistently by attempting to read a > broken floppy, and ejecting it while IO is being attempted and retried. > > To resolve this, this patch calls cancel_delayed_work() instead, which > cancels the work without waiting for the watchdog to return and finish. > > Before this regression was introduced, the code in this section used > del_timer(), and not del_timer_sync() to delete the watchdog timer. > > Fixes: 070ad7e793dc ("floppy: convert to delayed work and single-thread wq") > Signed-off-by: Tasos Sahanidis <tasos@tasossah.com> > --- > drivers/block/floppy.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c > index fef79ea52..85464d72d 100644 > --- a/drivers/block/floppy.c > +++ b/drivers/block/floppy.c > @@ -1014,7 +1014,7 @@ static DECLARE_DELAYED_WORK(fd_timer, fd_timer_workfn); > static void cancel_activity(void) > { > do_floppy = NULL; > - cancel_delayed_work_sync(&fd_timer); > + cancel_delayed_work(&fd_timer); > cancel_work_sync(&floppy_work); > } Sorry for the long response. Applied, thanks! https://github.com/evdenis/linux-floppy/commit/4258a7afaf3bde4441e844335170ee310ee29392 I will send it to Jens with other fixes. Regards, Denis
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c index fef79ea52..85464d72d 100644 --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -1014,7 +1014,7 @@ static DECLARE_DELAYED_WORK(fd_timer, fd_timer_workfn); static void cancel_activity(void) { do_floppy = NULL; - cancel_delayed_work_sync(&fd_timer); + cancel_delayed_work(&fd_timer); cancel_work_sync(&floppy_work); }
When the watchdog detects a disk change, it calls cancel_activity(), which in turn tries to cancel the fd_timer delayed work. In the above scenario, fd_timer_fn is set to fd_watchdog(), meaning it is trying to cancel its own work. This results in a hang as cancel_delayed_work_sync() is waiting for the watchdog (itself) to return, which never happens. This can be reproduced relatively consistently by attempting to read a broken floppy, and ejecting it while IO is being attempted and retried. To resolve this, this patch calls cancel_delayed_work() instead, which cancels the work without waiting for the watchdog to return and finish. Before this regression was introduced, the code in this section used del_timer(), and not del_timer_sync() to delete the watchdog timer. Fixes: 070ad7e793dc ("floppy: convert to delayed work and single-thread wq") Signed-off-by: Tasos Sahanidis <tasos@tasossah.com> --- drivers/block/floppy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)