Patch "hwtracing: hisi_ptt: Fix potential sleep in atomic context" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    hwtracing: hisi_ptt: Fix potential sleep in atomic context

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     hwtracing-hisi_ptt-fix-potential-sleep-in-atomic-con.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 7a422ad15e1c75f6fbd44c17e14c6fd5f2de1358
Author: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
Date:   Wed Jun 21 17:28:04 2023 +0800

    hwtracing: hisi_ptt: Fix potential sleep in atomic context
    
    [ Upstream commit 6c50384ef8b94a527445e3694ae6549e1f15d859 ]
    
    We're using pci_irq_vector() to obtain the interrupt number and then
    bind it to the CPU start perf under the protection of spinlock in
    pmu::start(). pci_irq_vector() might sleep since [1] because it will
    call msi_domain_get_virq() to get the MSI interrupt number and it
    needs to acquire dev->msi.data->mutex. Getting a mutex will sleep on
    contention. So use pci_irq_vector() in an atomic context is problematic.
    
    This patch cached the interrupt number in the probe() and uses the
    cached data instead to avoid potential sleep.
    
    [1] commit 82ff8e6b78fc ("PCI/MSI: Use msi_get_virq() in pci_get_vector()")
    
    Fixes: ff0de066b463 ("hwtracing: hisi_ptt: Add trace function support for HiSilicon PCIe Tune and Trace device")
    Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
    Signed-off-by: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
    Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
    Link: https://lore.kernel.org/r/20230621092804.15120-6-yangyicong@xxxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/hwtracing/ptt/hisi_ptt.c b/drivers/hwtracing/ptt/hisi_ptt.c
index 30f1525639b57..4140efd664097 100644
--- a/drivers/hwtracing/ptt/hisi_ptt.c
+++ b/drivers/hwtracing/ptt/hisi_ptt.c
@@ -341,13 +341,13 @@ static int hisi_ptt_register_irq(struct hisi_ptt *hisi_ptt)
 	if (ret < 0)
 		return ret;
 
-	ret = devm_request_threaded_irq(&pdev->dev,
-					pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ),
+	hisi_ptt->trace_irq = pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ);
+	ret = devm_request_threaded_irq(&pdev->dev, hisi_ptt->trace_irq,
 					NULL, hisi_ptt_isr, 0,
 					DRV_NAME, hisi_ptt);
 	if (ret) {
 		pci_err(pdev, "failed to request irq %d, ret = %d\n",
-			pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ), ret);
+			hisi_ptt->trace_irq, ret);
 		return ret;
 	}
 
@@ -757,8 +757,7 @@ static void hisi_ptt_pmu_start(struct perf_event *event, int flags)
 	 * core in event_function_local(). If CPU passed is offline we'll fail
 	 * here, just log it since we can do nothing here.
 	 */
-	ret = irq_set_affinity(pci_irq_vector(hisi_ptt->pdev, HISI_PTT_TRACE_DMA_IRQ),
-					      cpumask_of(cpu));
+	ret = irq_set_affinity(hisi_ptt->trace_irq, cpumask_of(cpu));
 	if (ret)
 		dev_warn(dev, "failed to set the affinity of trace interrupt\n");
 
@@ -1018,8 +1017,7 @@ static int hisi_ptt_cpu_teardown(unsigned int cpu, struct hlist_node *node)
 	 * Also make sure the interrupt bind to the migrated CPU as well. Warn
 	 * the user on failure here.
 	 */
-	if (irq_set_affinity(pci_irq_vector(hisi_ptt->pdev, HISI_PTT_TRACE_DMA_IRQ),
-					    cpumask_of(target)))
+	if (irq_set_affinity(hisi_ptt->trace_irq, cpumask_of(target)))
 		dev_warn(dev, "failed to set the affinity of trace interrupt\n");
 
 	hisi_ptt->trace_ctrl.on_cpu = target;
diff --git a/drivers/hwtracing/ptt/hisi_ptt.h b/drivers/hwtracing/ptt/hisi_ptt.h
index 5beb1648c93ab..948a4c4231527 100644
--- a/drivers/hwtracing/ptt/hisi_ptt.h
+++ b/drivers/hwtracing/ptt/hisi_ptt.h
@@ -166,6 +166,7 @@ struct hisi_ptt_pmu_buf {
  * @pdev:         pci_dev of this PTT device
  * @tune_lock:    lock to serialize the tune process
  * @pmu_lock:     lock to serialize the perf process
+ * @trace_irq:    interrupt number used by trace
  * @upper_bdf:    the upper BDF range of the PCI devices managed by this PTT device
  * @lower_bdf:    the lower BDF range of the PCI devices managed by this PTT device
  * @port_filters: the filter list of root ports
@@ -180,6 +181,7 @@ struct hisi_ptt {
 	struct pci_dev *pdev;
 	struct mutex tune_lock;
 	spinlock_t pmu_lock;
+	int trace_irq;
 	u32 upper_bdf;
 	u32 lower_bdf;