[PATCH] scsi: ufs: core: Avoid sleeping in hard interrupt context when PREEMP_RT is enabled.
From: Gregory CLEMENT
Date: Tue Jun 30 2026 - 05:58:55 EST
PREEMPT_RT turns spinlock in a mutex that cannot be used in interrupt
context. Since commit 3c7ac40d7322 ("scsi: ufs: core: Delegate the
interrupt service routine to a threaded IRQ handler"), the hard
interrupt handler is not converted into a threaded interrupt handler
(due to the IRQF_ONESHOT flag). This can lead to the use of a sleeping
function inside the interrupt context.
[ 0.654017] scsi host0: ufshcd
[ 0.659867] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
[ 0.659878] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/0
[ 0.659882] preempt_count: 10001, expected: 0
[ 0.659885] RCU nest depth: 0, expected: 0
[ 0.659892] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 7.1.0-rc3 #1 PREEMPT_RT
[ 0.659903] Call Trace:
[ 0.659907] [<ffffffff800148fe>] dump_backtrace+0x1c/0x24
[ 0.659924] [<ffffffff80001580>] show_stack+0x28/0x34
[ 0.659931] [<ffffffff8000ea7c>] dump_stack_lvl+0x5e/0x86
[ 0.659937] [<ffffffff8000eab8>] dump_stack+0x14/0x1c
[ 0.659942] [<ffffffff8005d07e>] __might_resched+0x138/0x142
[ 0.659956] [<ffffffff808bea82>] rt_spin_lock+0x38/0x144
[ 0.659965] [<ffffffff806d4b0a>] ufshcd_sl_intr+0x30a/0x622
[ 0.659973] [<ffffffff806d50bc>] ufshcd_intr+0x86/0x9c
[ 0.659979] [<ffffffff8009f072>] __handle_irq_event_percpu+0xa6/0x370
[ 0.659987] [<ffffffff8009f3d2>] handle_irq_event+0x42/0x98
[ 0.659992] [<ffffffff800a43ce>] handle_fasteoi_irq+0x11a/0x244
[ 0.660002] [<ffffffff8009e718>] handle_irq_desc+0x38/0x46
[ 0.660007] [<ffffffff8009e764>] generic_handle_irq+0x26/0x2e
[ 0.660013] [<ffffffff8054f1e2>] aplic_direct_handle_irq+0xa0/0x158
[ 0.660022] [<ffffffff8009e718>] handle_irq_desc+0x38/0x46
[ 0.660027] [<ffffffff8009e7f2>] generic_handle_domain_irq+0x12/0x1a
[ 0.660032] [<ffffffff8054df10>] riscv_intc_irq+0x2a/0x64
[ 0.660038] [<ffffffff808b2708>] handle_riscv_irq+0x52/0x82
[ 0.660048] [<ffffffff808c2fca>] call_on_irq_stack+0x32/0x40
This commit mitigates the issue by directly registering the thread
interrupt handler without involving a hard IRQ handler. This will only
be done when PREEMP_RT is enabled, which automatically turns all
interrupt handlers into threaded interrupt handlers.
Fixes: 3c7ac40d7322 ("scsi: ufs: core: Delegate the interrupt service routine to a threaded IRQ handler")
Signed-off-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxx>
---
drivers/ufs/core/ufshcd.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index d3044a3089b53..6d82658a1a66b 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -11235,9 +11235,17 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
*/
ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
- /* IRQ registration */
+ /* IRQ registration
+ * In the case of PREMMP_RT, directly use the threaded
+ * interrupt to avoid using a spinlock (which could sleep)
+ * in the hard IRQ handler.
+ */
+#ifdef CONFIG_PREEMPT_RT
+ err = devm_request_irq(dev, irq, ufshcd_threaded_intr, IRQF_SHARED, UFSHCD, hba);
+#else
err = devm_request_threaded_irq(dev, irq, ufshcd_intr, ufshcd_threaded_intr,
IRQF_ONESHOT | IRQF_SHARED, UFSHCD, hba);
+#endif
if (err) {
dev_err(hba->dev, "request irq failed\n");
goto out_disable;
---
base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482
change-id: 20260630-ufshcd-spinlock-sleep-fix-848811f28ad7
Best regards,
--
Grégory CLEMENT, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com