diff options
| author | Konstantin Khlebnikov <koct9i@gmail.com> | 2014-11-09 12:53:37 +0300 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2015-01-26 16:39:20 +0300 |
| commit | b3959c772ebaf1efedb44085c5bc43129704274b (patch) | |
| tree | a700349b351ce6cec88e976b724f50ee539173a7 /drivers/acpi/osl.c | |
| parent | 4d871c60d93292ab4a3b22192430de0c574e82e9 (diff) | |
| download | linux-b3959c772ebaf1efedb44085c5bc43129704274b.tar.xz | |
ACPI / osl: speedup grace period in acpi_os_map_cleanup
commit 74b51ee152b6d99e61ba329799a039453fb9438f upstream.
ACPI maintains cache of ioremap regions to speed up operations and
access to them from irq context where ioremap() calls aren't allowed.
This code abuses synchronize_rcu() on unmap path for synchronization
with fast-path in acpi_os_read/write_memory which uses this cache.
Since v3.10 CPUs are allowed to enter idle state even if they have RCU
callbacks queued, see commit c0f4dfd4f90f1667d234d21f15153ea09a2eaa66
("rcu: Make RCU_FAST_NO_HZ take advantage of numbered callbacks").
That change caused problems with nvidia proprietary driver which calls
acpi_os_map/unmap_generic_address several times during initialization.
Each unmap calls synchronize_rcu and adds significant delay. Totally
initialization is slowed for a couple of seconds and that is enough to
trigger timeout in hardware, gpu decides to "fell off the bus". Widely
spread workaround is reducing "rcu_idle_gp_delay" from 4 to 1 jiffy.
This patch replaces synchronize_rcu() with synchronize_rcu_expedited()
which is much faster.
Link: https://devtalk.nvidia.com/default/topic/567297/linux/linux-3-10-driver-crash/
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Reported-and-tested-by: Alexander Monakov <amonakov@gmail.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'drivers/acpi/osl.c')
| -rw-r--r-- | drivers/acpi/osl.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c index e5f416c7f66e..d73f85247272 100644 --- a/drivers/acpi/osl.c +++ b/drivers/acpi/osl.c @@ -421,7 +421,7 @@ static void acpi_os_drop_map_ref(struct acpi_ioremap *map) static void acpi_os_map_cleanup(struct acpi_ioremap *map) { if (!map->refcount) { - synchronize_rcu(); + synchronize_rcu_expedited(); acpi_unmap(map->phys, map->virt); kfree(map); } |