| From | Sasha Levin <> | Subject | [PATCH 5.12 071/110] s390: fix system call restart with multiple signals | Date | Mon, 28 Jun 2021 10:17:49 -0400 |
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From: Sven Schnelle <svens@linux.ibm.com>
commit fc66127dc3396338f287c3b494dfbf102547e770 upstream.
glibc complained with "The futex facility returned an unexpected error code.". It turned out that the futex syscall returned -ERESTARTSYS because a signal is pending. arch_do_signal_or_restart() restored the syscall parameters (nameley regs->gprs[2]) and set PIF_SYSCALL_RESTART. When another signal is made pending later in the exit loop arch_do_signal_or_restart() is called again. This function clears PIF_SYSCALL_RESTART and checks the return code which is set in regs->gprs[2]. However, regs->gprs[2] was restored in the previous run and no longer contains -ERESTARTSYS, so PIF_SYSCALL_RESTART isn't set again and the syscall is skipped.
Fix this by not clearing PIF_SYSCALL_RESTART - it is already cleared in __do_syscall() when the syscall is restarted.
Reported-by: Bjoern Walk <bwalk@linux.ibm.com> Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Fixes: 56e62a737028 ("s390: convert to generic entry") Cc: <stable@vger.kernel.org> # 5.12 Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/s390/kernel/signal.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c index 90163e6184f5..080e7aed181f 100644 --- a/arch/s390/kernel/signal.c +++ b/arch/s390/kernel/signal.c @@ -512,7 +512,6 @@ void arch_do_signal_or_restart(struct pt_regs *regs, bool has_signal) /* No handlers present - check for system call restart */ clear_pt_regs_flag(regs, PIF_SYSCALL); - clear_pt_regs_flag(regs, PIF_SYSCALL_RESTART); if (current->thread.system_call) { regs->int_code = current->thread.system_call; switch (regs->gprs[2]) { -- 2.30.2
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