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| author | Zhang Jianhua <chris.zjh@huawei.com> | 2021-09-23 10:53:40 +0800 |
|---|---|---|
| committer | Ard Biesheuvel <ardb@kernel.org> | 2021-10-05 13:07:01 +0200 |
| commit | 38fa3206bf441911258e5001ac8b6738693f8d82 (patch) | |
| tree | 22d72a846b2e5126e0b7092b2d4cb73a6d2e4635 /drivers/firmware | |
| parent | b3a72ca80351917cc23f9e24c35f3c3979d3c121 (diff) | |
| download | lwn-38fa3206bf441911258e5001ac8b6738693f8d82.tar.gz lwn-38fa3206bf441911258e5001ac8b6738693f8d82.zip | |
efi: Change down_interruptible() in virt_efi_reset_system() to down_trylock()
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>
Diffstat (limited to 'drivers/firmware')
| -rw-r--r-- | drivers/firmware/efi/runtime-wrappers.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c index 1410beaef5c3..f3e54f6616f0 100644 --- 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 reset_type, 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; |