path: root/kernel
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authorLinus Torvalds <>2020-02-22 17:25:46 -0800
committerLinus Torvalds <>2020-02-22 17:25:46 -0800
commitf3cc24942e955604232e3b4b0dac6a54cbc7c679 (patch)
tree7419b6244e8278f687b4156a05a7e6855d3bcfce /kernel
parentfca1037864a9fb75c9c48cb65649b24de8101ec4 (diff)
parent2546287c5fb363a0165933ae2181c92f03e701d0 (diff)
Merge tag 'irq-urgent-2020-02-22' of git://
Pull irq fixes from Thomas Gleixner: "Two fixes for the irq core code which are follow ups to the recent MSI fixes: - The WARN_ON which was put into the MSI setaffinity callback for paranoia reasons actually triggered via a callchain which escaped when all the possible ways to reach that code were analyzed. The proc/irq/$N/*affinity interfaces have a quirk which came in when ALPHA moved to the generic interface: In case that the written affinity mask does not contain any online CPU it calls into ALPHAs magic auto affinity setting code. A few years later this mechanism was also made available to x86 for no good reasons and in a way which circumvents all sanity checks for interrupts which cannot have their affinity set from process context on X86 due to the way the X86 interrupt delivery works. It would be possible to make this work properly, but there is no point in doing so. If the interrupt is not yet started then the affinity setting has no effect and if it is started already then it is already assigned to an online CPU so there is no point to randomly move it to some other CPU. Just return EINVAL as the code has done before that change forever. - The new MSI quirk bit in the irq domain flags turned out to be already occupied, which escaped the author and the reviewers because the already in use bits were 0,6,2,3,4,5 listed in that order. That bit 6 was simply overlooked because the ordering was straight forward linear otherwise. So the new bit ended up being a duplicate. Fix it up by switching the oddball 6 to the obvious 1" * tag 'irq-urgent-2020-02-22' of git:// genirq/irqdomain: Make sure all irq domain flags are distinct genirq/proc: Reject invalid affinity masks (again)
Diffstat (limited to 'kernel')
3 files changed, 24 insertions, 18 deletions
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 3924fbe829d4..c9d8eb7f5c02 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -128,8 +128,6 @@ static inline void unregister_handler_proc(unsigned int irq,
extern bool irq_can_set_affinity_usr(unsigned int irq);
-extern int irq_select_affinity_usr(unsigned int irq);
extern void irq_set_thread_affinity(struct irq_desc *desc);
extern int irq_do_set_affinity(struct irq_data *data,
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 3089a60ea8f9..7eee98c38f25 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -481,23 +481,9 @@ int irq_setup_affinity(struct irq_desc *desc)
return irq_select_affinity(irq_desc_get_irq(desc));
+#endif /* CONFIG_SMP */
- * Called when a bogus affinity is set via /proc/irq
- */
-int irq_select_affinity_usr(unsigned int irq)
- struct irq_desc *desc = irq_to_desc(irq);
- unsigned long flags;
- int ret;
- raw_spin_lock_irqsave(&desc->lock, flags);
- ret = irq_setup_affinity(desc);
- raw_spin_unlock_irqrestore(&desc->lock, flags);
- return ret;
* irq_set_vcpu_affinity - Set vcpu affinity for the interrupt
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 9e5783d98033..32c071d7bc03 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -111,6 +111,28 @@ static int irq_affinity_list_proc_show(struct seq_file *m, void *v)
return show_irq_affinity(AFFINITY_LIST, m);
+static inline int irq_select_affinity_usr(unsigned int irq)
+ /*
+ * If the interrupt is started up already then this fails. The
+ * interrupt is assigned to an online CPU already. There is no
+ * point to move it around randomly. Tell user space that the
+ * selected mask is bogus.
+ *
+ * If not then any change to the affinity is pointless because the
+ * startup code invokes irq_setup_affinity() which will select
+ * a online CPU anyway.
+ */
+ return -EINVAL;
+/* ALPHA magic affinity auto selector. Keep it for historical reasons. */
+static inline int irq_select_affinity_usr(unsigned int irq)
+ return irq_select_affinity(irq);
static ssize_t write_irq_affinity(int type, struct file *file,
const char __user *buffer, size_t count, loff_t *pos)