diff options
| author | Yeoreum Yun <yeoreum.yun@arm.com> | 2025-12-17 08:51:15 +0000 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2025-12-23 15:28:34 +0100 |
| commit | 6402078bd9d1ed46e79465e1faaa42e3458f8a33 (patch) | |
| tree | 689b577e02a006a34df84084859b33b84c62e220 /drivers/net | |
| parent | 2a2618c050e70d1155cb0ec53197257dc3a56690 (diff) | |
smc91x: fix broken irq-context in PREEMPT_RT
When smc91x.c is built with PREEMPT_RT, the following splat occurs
in FVP_RevC:
[ 13.055000] smc91x LNRO0003:00 eth0: link up, 10Mbps, half-duplex, lpa 0x0000
[ 13.062137] BUG: workqueue leaked atomic, lock or RCU: kworker/2:1[106]
[ 13.062137] preempt=0x00000000 lock=0->0 RCU=0->1 workfn=mld_ifc_work
[ 13.062266] C
** replaying previous printk message **
[ 13.062266] CPU: 2 UID: 0 PID: 106 Comm: kworker/2:1 Not tainted 6.18.0-dirty #179 PREEMPT_{RT,(full)}
[ 13.062353] Hardware name: , BIOS
[ 13.062382] Workqueue: mld mld_ifc_work
[ 13.062469] Call trace:
[ 13.062494] show_stack+0x24/0x40 (C)
[ 13.062602] __dump_stack+0x28/0x48
[ 13.062710] dump_stack_lvl+0x7c/0xb0
[ 13.062818] dump_stack+0x18/0x34
[ 13.062926] process_scheduled_works+0x294/0x450
[ 13.063043] worker_thread+0x260/0x3d8
[ 13.063124] kthread+0x1c4/0x228
[ 13.063235] ret_from_fork+0x10/0x20
This happens because smc_special_trylock() disables IRQs even on PREEMPT_RT,
but smc_special_unlock() does not restore IRQs on PREEMPT_RT.
The reason is that smc_special_unlock() calls spin_unlock_irqrestore(),
and rcu_read_unlock_bh() in __dev_queue_xmit() cannot invoke
rcu_read_unlock() through __local_bh_enable_ip() when current->softirq_disable_cnt becomes zero.
To address this issue, replace smc_special_trylock() with spin_trylock_irqsave().
Fixes: 342a93247e08 ("locking/spinlock: Provide RT variant header: <linux/spinlock_rt.h>")
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20251217085115.1730036-1-yeoreum.yun@arm.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'drivers/net')
| -rw-r--r-- | drivers/net/ethernet/smsc/smc91x.c | 10 |
1 files changed, 1 insertions, 9 deletions
diff --git a/drivers/net/ethernet/smsc/smc91x.c b/drivers/net/ethernet/smsc/smc91x.c index 9d1a83a5fa7e..d16c178d1034 100644 --- a/drivers/net/ethernet/smsc/smc91x.c +++ b/drivers/net/ethernet/smsc/smc91x.c @@ -516,15 +516,7 @@ static inline void smc_rcv(struct net_device *dev) * any other concurrent access and C would always interrupt B. But life * isn't that easy in a SMP world... */ -#define smc_special_trylock(lock, flags) \ -({ \ - int __ret; \ - local_irq_save(flags); \ - __ret = spin_trylock(lock); \ - if (!__ret) \ - local_irq_restore(flags); \ - __ret; \ -}) +#define smc_special_trylock(lock, flags) spin_trylock_irqsave(lock, flags) #define smc_special_lock(lock, flags) spin_lock_irqsave(lock, flags) #define smc_special_unlock(lock, flags) spin_unlock_irqrestore(lock, flags) #else |