| From 38fa3206bf441911258e5001ac8b6738693f8d82 Mon Sep 17 00:00:00 2001 |
| From: Zhang Jianhua <chris.zjh@huawei.com> |
| Date: Thu, 23 Sep 2021 10:53:40 +0800 |
| Subject: efi: Change down_interruptible() in virt_efi_reset_system() to down_trylock() |
| |
| From: Zhang Jianhua <chris.zjh@huawei.com> |
| |
| commit 38fa3206bf441911258e5001ac8b6738693f8d82 upstream. |
| |
| While reboot the system by sysrq, the following bug will be occur. |
| |
| BUG: sleeping function called from invalid context at kernel/locking/semaphore.c:90 |
| in_atomic(): 0, irqs_disabled(): 128, non_block: 0, pid: 10052, name: rc.shutdown |
| CPU: 3 PID: 10052 Comm: rc.shutdown Tainted: G W O 5.10.0 #1 |
| Call trace: |
| dump_backtrace+0x0/0x1c8 |
| show_stack+0x18/0x28 |
| dump_stack+0xd0/0x110 |
| ___might_sleep+0x14c/0x160 |
| __might_sleep+0x74/0x88 |
| down_interruptible+0x40/0x118 |
| virt_efi_reset_system+0x3c/0xd0 |
| efi_reboot+0xd4/0x11c |
| machine_restart+0x60/0x9c |
| emergency_restart+0x1c/0x2c |
| sysrq_handle_reboot+0x1c/0x2c |
| __handle_sysrq+0xd0/0x194 |
| write_sysrq_trigger+0xbc/0xe4 |
| proc_reg_write+0xd4/0xf0 |
| vfs_write+0xa8/0x148 |
| ksys_write+0x6c/0xd8 |
| __arm64_sys_write+0x18/0x28 |
| el0_svc_common.constprop.3+0xe4/0x16c |
| do_el0_svc+0x1c/0x2c |
| el0_svc+0x20/0x30 |
| el0_sync_handler+0x80/0x17c |
| el0_sync+0x158/0x180 |
| |
| The reason for this problem is that irq has been disabled in |
| machine_restart() and then it calls down_interruptible() in |
| virt_efi_reset_system(), which would occur sleep in irq context, |
| it is dangerous! Commit 99409b935c9a("locking/semaphore: Add |
| might_sleep() to down_*() family") add might_sleep() in |
| down_interruptible(), so the bug info is here. down_trylock() |
| can solve this problem, cause there is no might_sleep. |
| |
| -------- |
| |
| Cc: <stable@vger.kernel.org> |
| Signed-off-by: Zhang Jianhua <chris.zjh@huawei.com> |
| Signed-off-by: Ard Biesheuvel <ardb@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/firmware/efi/runtime-wrappers.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/drivers/firmware/efi/runtime-wrappers.c |
| +++ b/drivers/firmware/efi/runtime-wrappers.c |
| @@ -414,7 +414,7 @@ static void virt_efi_reset_system(int re |
| unsigned long data_size, |
| efi_char16_t *data) |
| { |
| - if (down_interruptible(&efi_runtime_lock)) { |
| + if (down_trylock(&efi_runtime_lock)) { |
| pr_warn("failed to invoke the reset_system() runtime service:\n" |
| "could not get exclusive access to the firmware\n"); |
| return; |