Messages in this thread Patch in this message | | | From | Julien Grall <> | Subject | [PATCH] tty/sysrq: Convert show_lock to raw_spinlock_t | Date | Mon, 4 Mar 2019 17:20:53 +0000 |
| |
At the moment show_lock is implemented using spin_lock_t and called from an interrupt context on Arm64. The following backtrace was triggered by:
42sh# echo l > /proc/sysrq-trigger
[ 4432.073756] sysrq: SysRq : Show backtrace of all active CPUs [ 4432.403422] BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:974 [ 4432.403424] sysrq: CPU6: [ 4432.403426] in_atomic(): 1, irqs_disabled(): 128, pid: 2410, name: kworker/u16:2
[...]
[ 4432.403581] Call trace: [ 4432.403584] dump_backtrace+0x0/0x148 [ 4432.403586] show_stack+0x14/0x20 [ 4432.403588] dump_stack+0x9c/0xd4 [ 4432.403592] ___might_sleep+0x1cc/0x298 [ 4432.403595] rt_spin_lock+0x5c/0x70 [ 4432.403596] showacpu+0x34/0x68 [ 4432.403599] flush_smp_call_function_queue+0xd4/0x278 [ 4432.403602] generic_smp_call_function_single_interrupt+0x10/0x18 [ 4432.403605] handle_IPI+0x26c/0x668 [ 4432.403607] gic_handle_irq+0x9c/0xa0 [ 4432.403609] el1_irq+0xb4/0x13c
With RT-patches, spin_lock can now sleep and therefore cannot be used from interrupt context. Use a raw_spin_lock instead to prevent the lock to sleep.
Signed-off-by: Julien Grall <julien.grall@arm.com> --- drivers/tty/sysrq.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 1f03078ec352..8473557c7ab2 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -208,7 +208,7 @@ static struct sysrq_key_op sysrq_showlocks_op = { #endif #ifdef CONFIG_SMP -static DEFINE_SPINLOCK(show_lock); +static DEFINE_RAW_SPINLOCK(show_lock); static void showacpu(void *dummy) { @@ -218,10 +218,10 @@ static void showacpu(void *dummy) if (idle_cpu(smp_processor_id())) return; - spin_lock_irqsave(&show_lock, flags); + raw_spin_lock_irqsave(&show_lock, flags); pr_info("CPU%d:\n", smp_processor_id()); show_stack(NULL, NULL); - spin_unlock_irqrestore(&show_lock, flags); + raw_spin_unlock_irqrestore(&show_lock, flags); } static void sysrq_showregs_othercpus(struct work_struct *dummy) -- 2.11.0
| |