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| author | Ben Hutchings <ben@decadent.org.uk> | 2015-09-26 12:23:56 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-10-22 14:37:53 -0700 |
| commit | 8938c10543801cbb9d85efd3f317184e405b45bc (patch) | |
| tree | babbc06820699c8d50a00a597d46250ff062016e | |
| parent | e9346b9a2f5cd4ff470ee58d1bf271d0a2ca27a0 (diff) | |
| download | lwn-8938c10543801cbb9d85efd3f317184e405b45bc.tar.gz lwn-8938c10543801cbb9d85efd3f317184e405b45bc.zip | |
genirq: Fix race in register_irq_proc()
commit 95c2b17534654829db428f11bcf4297c059a2a7e upstream.
Per-IRQ directories in procfs are created only when a handler is first
added to the irqdesc, not when the irqdesc is created. In the case of
a shared IRQ, multiple tasks can race to create a directory. This
race condition seems to have been present forever, but is easier to
hit with async probing.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Link: http://lkml.kernel.org/r/1443266636.2004.2.camel@decadent.org.uk
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/irq/proc.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c index 19ed5c425c3b..349e5bbdb31f 100644 --- a/kernel/irq/proc.c +++ b/kernel/irq/proc.c @@ -12,6 +12,7 @@ #include <linux/seq_file.h> #include <linux/interrupt.h> #include <linux/kernel_stat.h> +#include <linux/mutex.h> #include "internals.h" @@ -309,18 +310,29 @@ void register_handler_proc(unsigned int irq, struct irqaction *action) void register_irq_proc(unsigned int irq, struct irq_desc *desc) { + static DEFINE_MUTEX(register_lock); char name [MAX_NAMELEN]; - if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip) || desc->dir) + if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip)) return; + /* + * irq directories are registered only when a handler is + * added, not when the descriptor is created, so multiple + * tasks might try to register at the same time. + */ + mutex_lock(®ister_lock); + + if (desc->dir) + goto out_unlock; + memset(name, 0, MAX_NAMELEN); sprintf(name, "%d", irq); /* create /proc/irq/1234 */ desc->dir = proc_mkdir(name, root_irq_dir); if (!desc->dir) - return; + goto out_unlock; #ifdef CONFIG_SMP /* create /proc/irq/<irq>/smp_affinity */ @@ -341,6 +353,9 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc) proc_create_data("spurious", 0444, desc->dir, &irq_spurious_proc_fops, (void *)(long)irq); + +out_unlock: + mutex_unlock(®ister_lock); } void unregister_irq_proc(unsigned int irq, struct irq_desc *desc) |