Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 95c2b175 authored by Ben Hutchings's avatar Ben Hutchings Committed by Thomas Gleixner
Browse files

genirq: Fix race in register_irq_proc() 



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: default avatarBen Hutchings <ben@decadent.org.uk>
Link: http://lkml.kernel.org/r/1443266636.2004.2.camel@decadent.org.uk


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
parent d32dc9aa

kernel/irq/proc.c

+17 −2
Original line number Diff line number Diff line
@@ -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"
@@ -323,18 +324,29 @@ 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(&register_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 */
@@ -355,6 +367,9 @@ 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(&register_lock);

}



void unregister_irq_proc(unsigned int irq, struct irq_desc *desc)