linux-toradex.git/kernel/irq/proc.c, branch v3.2.73

genirq: Fix race in register_irq_proc()

2015-11-17T15:54:41+00:00

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 
Link: http://lkml.kernel.org/r/1443266636.2004.2.camel@decadent.org.uk
Signed-off-by: Thomas Gleixner

genirq: Prevent proc race against freeing of irq descriptors

2015-02-20T00:49:30+00:00

commit c291ee622165cb2c8d4e7af63fffd499354a23be upstream.

Since the rework of the sparse interrupt code to actually free the
unused interrupt descriptors there exists a race between the /proc
interfaces to the irq subsystem and the code which frees the interrupt
descriptor.

CPU0				CPU1
				show_interrupts()
				  desc = irq_to_desc(X);
free_desc(desc)
  remove_from_radix_tree();
  kfree(desc);
				  raw_spinlock_irq(&desc->lock);

/proc/interrupts is the only interface which can actively corrupt
kernel memory via the lock access. /proc/stat can only read from freed
memory. Extremly hard to trigger, but possible.

The interfaces in /proc/irq/N/ are not affected by this because the
removal of the proc file is serialized in procfs against concurrent
readers/writers. The removal happens before the descriptor is freed.

For architectures which have CONFIG_SPARSE_IRQ=n this is a non issue
as the descriptor is never freed. It's merely cleared out with the irq
descriptor lock held. So any concurrent proc access will either see
the old correct value or the cleared out ones.

Protect the lookup and access to the irq descriptor in
show_interrupts() with the sparse_irq_lock.

Provide kstat_irqs_usr() which is protecting the lookup and access
with sparse_irq_lock and switch /proc/stat to use it.

Document the existing kstat_irqs interfaces so it's clear that the
caller needs to take care about protection. The users of these
interfaces are either not affected due to SPARSE_IRQ=n or already
protected against removal.

Fixes: 1f5a5b87f78f "genirq: Implement a sane sparse_irq allocator"
Signed-off-by: Thomas Gleixner 
[bwh: Backported to 3.2:
 - Adjust context
 - Handle the CONFIG_GENERIC_HARDIRQS=n case]
Signed-off-by: Ben Hutchings

irq: Remove smp_affinity_list when unregister irq proc

2011-05-26T11:15:28+00:00

commit 4b06042(bitmap, irq: add smp_affinity_list interface to
/proc/irq) causes the following warning:

[  274.239500] WARNING: at fs/proc/generic.c:850 remove_proc_entry+0x24c/0x27a()
[  274.251761] remove_proc_entry: removing non-empty directory 'irq/184',
    	       leaking at least 'smp_affinity_list'

Remove the new file in the exit path.

Signed-off-by: Yinghai Lu 
Cc: Mike Travis 
Link: http://lkml.kernel.org/r/4DDDE094.6050505@kernel.org
Signed-off-by: Thomas Gleixner

bitmap, irq: add smp_affinity_list interface to /proc/irq

2011-05-25T15:39:45+00:00

Manually adjusting the smp_affinity for IRQ's becomes unwieldy when the
cpu count is large.

Setting smp affinity to cpus 256 to 263 would be:

	echo 000000ff,00000000,00000000,00000000,00000000,00000000,00000000,00000000 > smp_affinity

instead of:

	echo 256-263 > smp_affinity_list

Think about what it looks like for cpus around say, 4088 to 4095.

We already have many alternate "list" interfaces:

/sys/devices/system/cpu/cpuX/indexY/shared_cpu_list
/sys/devices/system/cpu/cpuX/topology/thread_siblings_list
/sys/devices/system/cpu/cpuX/topology/core_siblings_list
/sys/devices/system/node/nodeX/cpulist
/sys/devices/pci***/***/local_cpulist

Add a companion interface, smp_affinity_list to use cpu lists instead of
cpu maps.  This conforms to other companion interfaces where both a map
and a list interface exists.

This required adding a bitmap_parselist_user() function in a manner
similar to the bitmap_parse_user() function.

[akpm@linux-foundation.org: make __bitmap_parselist() static]
Signed-off-by: Mike Travis 
Cc: Thomas Gleixner 
Cc: Jack Steiner 
Cc: Lee Schermerhorn 
Cc: Andy Shevchenko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

genirq: Fix typo CONFIG_GENIRC_IRQ_SHOW_LEVEL

2011-05-02T19:16:37+00:00

commit ab7798ffcf98b11a9525cf65bacdae3fd58d357f ("genirq: Expand generic
show_interrupts()") added the Kconfig option GENERIC_IRQ_SHOW_LEVEL to
accomodate PowerPC, but this doesn't actually enable the functionality due
to a typo in the #ifdef check.

Signed-off-by: Geert Uytterhoeven 
Cc: Linux/PPC Development 
Link: http://lkml.kernel.org/r/%3Calpine.DEB.2.00.1104302251370.19068%40ayla.of.borg%3E
Signed-off-by: Thomas Gleixner

alpha: Use generic show_interrupts()

2011-03-29T12:47:58+00:00

The only subtle difference is that alpha uses ACTUAL_NR_IRQS and
prints the IRQF_DISABLED flag.

Change the generic implementation to deal with ACTUAL_NR_IRQS if
defined.

The IRQF_DISABLED printing is pointless, as we nowadays run all
interrupts with irqs disabled.

Signed-off-by: Thomas Gleixner

genirq: Expand generic show_interrupts()

2011-03-25T16:04:20+00:00

Some archs want to print extra information for certain irq_chips which
is per irq and not per chip. Allow them to provide a chip callback to
print the chip name and the extra information.

PowerPC wants to print the LEVEL/EDGE type information. Make it configurable.

Signed-off-by: Thomas Gleixner

genirq: show_interrupts: Check desc->name before printing it blindly

2011-03-17T14:52:19+00:00

desc->name is not required and not used by all architectures.

Signed-off-by: Thomas Gleixner

genirq: Reuse existing can set affinty check

2011-02-19T11:58:20+00:00

Add a !desc check while at it.

Signed-off-by: Thomas Gleixner

genirq: Add IRQ_MOVE_PENDING to irq_data.state

2011-02-19T11:58:18+00:00

chip implementations need to know about it. Keep status in sync until
all users are fixed. 

Accessor function: irqd_is_setaffinity_pending(irqdata)

Coders who access them directly will be tracked down and slapped with
stinking trouts.

Signed-off-by: Thomas Gleixner