Messages in this thread | | | From | Mark Tomlinson <> | Subject | Re: [PATCH RESEND] tty/sysrq: Do not call sync directly from sysrq_do_reset() | Date | Tue, 27 Nov 2018 19:58:17 +0000 |
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On 27/11/18 11:11 PM, Greg KH wrote: > On Tue, Nov 27, 2018 at 09:57:23AM +1300, Mark Tomlinson wrote: >> sysrq_do_reset() is called in softirq context, so it cannot call >> sync() directly. Instead, call orderly_reboot(), which creates a work >> item to run /sbin/reboot, or do emergency_sync and restart if the >> command fails. >> >> Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz> >> --- >> drivers/tty/sysrq.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c >> index ad1ee5d01b53..f2ca32c1ad7c 100644 >> --- a/drivers/tty/sysrq.c >> +++ b/drivers/tty/sysrq.c >> @@ -660,8 +660,7 @@ static void sysrq_do_reset(struct timer_list *t) >> >> state->reset_requested = true; >> >> - ksys_sync(); >> - kernel_restart(NULL); >> + orderly_reboot(); > > Is this something new? Why haven't we had reports of this failing in > the past? Or has something changed recently to cause this to now be > needed? > > thanks, > > greg k-h >
As far as I can tell, sysrq_do_reset() is only used when setting the "keyset" property in "/chosen/linux,sysrq-reset-seq" (which is what I want to do). No DTS file in the kernel tree sets this, so I don't know if anyone else is using this. I am wondering whether it ever worked. A reboot does occur after a kernel panic, so if the console is not available, it may appear to have worked.
Pressing the standard 'sysrq' key followed by 'b'(reboot) instead calls sysrq_handle_reboot(), which does not call sync at all, but emergency_restart(). Also, the 's'(sync) key calls emergency_sync(), which performs the sync via a work queue.
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