From: Matthias Kaehlcke Date: Thu, 20 Sep 2018 17:12:53 +0000 (-0700) Subject: sysrq: Use panic() to force a crash X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=8341f2f222d7;p=linux.git sysrq: Use panic() to force a crash sysrq_handle_crash() currently forces a crash by dereferencing a NULL pointer, which is undefined behavior in C. Just call panic() instead, which is simpler and doesn't depend on compiler specific handling of the undefined behavior. Remove the comment on why the RCU lock needs to be released, it isn't accurate anymore since the crash now isn't handled by the page fault handler (for reference: the comment was added by commit 984cf355aeaa ("sysrq: Fix warning in sysrq generated crash.")). Releasing the lock is still good practice though. Suggested-by: Greg Kroah-Hartman Signed-off-by: Matthias Kaehlcke Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 4bba54e622041..28fb20e9f9845 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -134,17 +134,10 @@ static struct sysrq_key_op sysrq_unraw_op = { static void sysrq_handle_crash(int key) { - char *killer = NULL; - - /* we need to release the RCU read lock here, - * otherwise we get an annoying - * 'BUG: sleeping function called from invalid context' - * complaint from the kernel before the panic. - */ + /* release the RCU read lock before crashing */ rcu_read_unlock(); - panic_on_oops = 1; /* force panic */ - wmb(); - *killer = 1; + + panic("sysrq triggered crash\n"); } static struct sysrq_key_op sysrq_crash_op = { .handler = sysrq_handle_crash,