Eric Lee / smarc-ti-linux-kernel

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Commit 83db93f4de2d9ae441a491d1dc61c2204f0195de

Authored by Neil Brown
Committed by Greg Kroah-Hartman
1 parent a6a8357788
Exists in master and in 20 other branches dlt-processor-sdk-linux-03.00.00.04, newt-ti-linux-3.12.y, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.12.10, smarc-ti-linux-3.12.y, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.12.y, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

sysfs: Allow sysfs_notify_dirent to be called from interrupt context. 

sysfs_notify_dirent is a simple atomic operation that can be used to
alert user-space that new data can be read from a sysfs attribute.

Unfortunately it cannot currently be called from non-process context
because of its use of spin_lock which is sometimes taken with
interrupts enabled.

So change all lockers of sysfs_open_dirent_lock to disable interrupts,
thus making sysfs_notify_dirent safe to be called from non-process
context (as drivers/md does in md_safemode_timeout).

sysfs_get_open_dirent is (documented as being) only called from
process context, so it uses spin_lock_irq.  Other places
use spin_lock_irqsave.

The usage for sysfs_notify_dirent in md_safemode_timeout was
introduced in 2.6.28, so this patch is suitable for that and more
recent kernels.

Reported-by: Joel Andres Granados <jgranado@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Showing 1 changed file with 8 additions and 6 deletions Side-by-side Diff

... ... @@ -268,7 +268,7 @@
268 268 struct sysfs_open_dirent *od, *new_od = NULL;
269 269  
270 270 retry:
271   - spin_lock(&sysfs_open_dirent_lock);
  271 + spin_lock_irq(&sysfs_open_dirent_lock);
272 272  
273 273 if (!sd->s_attr.open && new_od) {
274 274 sd->s_attr.open = new_od;
... ... @@ -281,7 +281,7 @@
281 281 list_add_tail(&buffer->list, &od->buffers);
282 282 }
283 283  
284   - spin_unlock(&sysfs_open_dirent_lock);
  284 + spin_unlock_irq(&sysfs_open_dirent_lock);
285 285  
286 286 if (od) {
287 287 kfree(new_od);
288 288  
... ... @@ -315,8 +315,9 @@
315 315 struct sysfs_buffer *buffer)
316 316 {
317 317 struct sysfs_open_dirent *od = sd->s_attr.open;
  318 + unsigned long flags;
318 319  
319   - spin_lock(&sysfs_open_dirent_lock);
  320 + spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
320 321  
321 322 list_del(&buffer->list);
322 323 if (atomic_dec_and_test(&od->refcnt))
... ... @@ -324,7 +325,7 @@
324 325 else
325 326 od = NULL;
326 327  
327   - spin_unlock(&sysfs_open_dirent_lock);
  328 + spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
328 329  
329 330 kfree(od);
330 331 }
331 332  
... ... @@ -456,8 +457,9 @@
456 457 void sysfs_notify_dirent(struct sysfs_dirent *sd)
457 458 {
458 459 struct sysfs_open_dirent *od;
  460 + unsigned long flags;
459 461  
460   - spin_lock(&sysfs_open_dirent_lock);
  462 + spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
461 463  
462 464 od = sd->s_attr.open;
463 465 if (od) {
... ... @@ -465,7 +467,7 @@
465 467 wake_up_interruptible(&od->poll);
466 468 }
467 469  
468   - spin_unlock(&sysfs_open_dirent_lock);
  470 + spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
469 471 }
470 472 EXPORT_SYMBOL_GPL(sysfs_notify_dirent);
471 473