Patch "coresight: trbe: Fix TRBE potential sleep in atomic context" has been added to the 6.4-stable tree

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

    coresight: trbe: Fix TRBE potential sleep in atomic context

to the 6.4-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:
     coresight-trbe-fix-trbe-potential-sleep-in-atomic-co.patch
and it can be found in the queue-6.4 subdirectory.

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



commit 008fd7a855d86ebc0d50df577d9b6be299c26a98
Author: Junhao He <hejunhao3@xxxxxxxxxx>
Date:   Fri Aug 18 16:40:52 2023 +0800

    coresight: trbe: Fix TRBE potential sleep in atomic context
    
    [ Upstream commit c0a232f1e19e378c5c4e5973a996392942c80090 ]
    
    smp_call_function_single() will allocate an IPI interrupt vector to
    the target processor and send a function call request to the interrupt
    vector. After the target processor receives the IPI interrupt, it will
    execute arm_trbe_remove_coresight_cpu() call request in the interrupt
    handler.
    
    According to the device_unregister() stack information, if other process
    is useing the device, the down_write() may sleep, and trigger deadlocks
    or unexpected errors.
    
      arm_trbe_remove_coresight_cpu
        coresight_unregister
          device_unregister
            device_del
              kobject_del
                __kobject_del
                  sysfs_remove_dir
                    kernfs_remove
                      down_write ---------> it may sleep
    
    Add a helper arm_trbe_disable_cpu() to disable TRBE precpu irq and reset
    per TRBE.
    Simply call arm_trbe_remove_coresight_cpu() directly without useing the
    smp_call_function_single(), which is the same as registering the TRBE
    coresight device.
    
    Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
    Signed-off-by: Junhao He <hejunhao3@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230814093813.19152-2-hejunhao3@xxxxxxxxxx
    [ Remove duplicate cpumask checks during removal ]
    Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
    [ v3 - Remove the operation of assigning NULL to cpudata->drvdata ]
    Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
    Link: https://lore.kernel.org/r/20230818084052.10116-1-hejunhao3@xxxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 1fc4fd79a1c69..925f6c9cecff4 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -1223,6 +1223,16 @@ static void arm_trbe_enable_cpu(void *info)
 	enable_percpu_irq(drvdata->irq, IRQ_TYPE_NONE);
 }
 
+static void arm_trbe_disable_cpu(void *info)
+{
+	struct trbe_drvdata *drvdata = info;
+	struct trbe_cpudata *cpudata = this_cpu_ptr(drvdata->cpudata);
+
+	disable_percpu_irq(drvdata->irq);
+	trbe_reset_local(cpudata);
+}
+
+
 static void arm_trbe_register_coresight_cpu(struct trbe_drvdata *drvdata, int cpu)
 {
 	struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
@@ -1324,18 +1334,12 @@ static void arm_trbe_probe_cpu(void *info)
 	cpumask_clear_cpu(cpu, &drvdata->supported_cpus);
 }
 
-static void arm_trbe_remove_coresight_cpu(void *info)
+static void arm_trbe_remove_coresight_cpu(struct trbe_drvdata *drvdata, int cpu)
 {
-	int cpu = smp_processor_id();
-	struct trbe_drvdata *drvdata = info;
-	struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
 	struct coresight_device *trbe_csdev = coresight_get_percpu_sink(cpu);
 
-	disable_percpu_irq(drvdata->irq);
-	trbe_reset_local(cpudata);
 	if (trbe_csdev) {
 		coresight_unregister(trbe_csdev);
-		cpudata->drvdata = NULL;
 		coresight_set_percpu_sink(cpu, NULL);
 	}
 }
@@ -1364,8 +1368,10 @@ static int arm_trbe_remove_coresight(struct trbe_drvdata *drvdata)
 {
 	int cpu;
 
-	for_each_cpu(cpu, &drvdata->supported_cpus)
-		smp_call_function_single(cpu, arm_trbe_remove_coresight_cpu, drvdata, 1);
+	for_each_cpu(cpu, &drvdata->supported_cpus) {
+		smp_call_function_single(cpu, arm_trbe_disable_cpu, drvdata, 1);
+		arm_trbe_remove_coresight_cpu(drvdata, cpu);
+	}
 	free_percpu(drvdata->cpudata);
 	return 0;
 }
@@ -1404,12 +1410,8 @@ static int arm_trbe_cpu_teardown(unsigned int cpu, struct hlist_node *node)
 {
 	struct trbe_drvdata *drvdata = hlist_entry_safe(node, struct trbe_drvdata, hotplug_node);
 
-	if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) {
-		struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
-
-		disable_percpu_irq(drvdata->irq);
-		trbe_reset_local(cpudata);
-	}
+	if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
+		arm_trbe_disable_cpu(drvdata);
 	return 0;
 }
 



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