linux-stable.git/drivers/acpi/ec.c, branch linux-4.1.y

ACPI / EC: fix NULL pointer dereference in acpi_ec_remove_query_handler()

2015-04-22T02:12:35+00:00

Use list_for_each_entry_safe for iterating because handler may be freed
in the loop.

BUG: unable to handle kernel NULL pointer dereference at 000000000000002c
IP: [] acpi_ec_put_query_handler+0x7/0x1a
Call Trace:
 acpi_ec_remove_query_handler+0x87/0x97
 acpi_smbus_hc_remove+0x2a/0x44 [sbshc]
 acpi_device_remove+0x7b/0x9a
 __device_release_driver+0x7e/0x110
 driver_detach+0xb0/0xc0
 bus_remove_driver+0x54/0xe0
 driver_unregister+0x2b/0x60
 acpi_bus_unregister_driver+0x10/0x12
 acpi_smb_hc_driver_exit+0x10/0x12 [sbshc]
 SyS_delete_module+0x1b8/0x210
 system_call_fastpath+0x12/0x6a

Signed-off-by: Chris Bainbridge 
Signed-off-by: Rafael J. Wysocki

ACPI / EC: Call acpi_walk_dep_device_list() after installing EC opregion handler

2015-04-02T00:21:41+00:00

On some machines(E,G Mircosoft surface 3), ACPI battery depends on
the EC operation region and it has _DEP method which contains EC.
Current code doesn't support such devices whose dep_unmet will be
not be decreased after EC opregion handler being installed. This
blocks battery device to be attached with its driver. This patch
is to fix the issue.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=90161
Reported-and-tested-by: Lompik 
Tested-by: Valentin Lab 
Signed-off-by: Lan Tianyu 
Signed-off-by: Rafael J. Wysocki

ACPI / EC: Add GPE reference counting debugging messages.

2015-03-09T23:58:37+00:00

This patch enhances debugging with the GPE reference count messages added.

This kind of log entries can be used by the platform validators to validate
if there is an EC transaction broken because of firmware/driver bugs.

No functional changes.

Signed-off-by: Lv Zheng 
Signed-off-by: Rafael J. Wysocki

ACPI / EC: Cleanup logging/debugging splitter support.

2015-03-09T23:58:36+00:00

This patch refines logging/debugging splitter support so that when DEBUG is
disabled, splitters won't be visible in the kernel logs while they are
still available for developers when DEBUG is enabled.

This patch also refines the splitters to mark the following handling
process boundaries:
  +++++: boundary of driver starting/stopping
         boundary of IRQ storming
  =====: boundary of transaction advancement
  *****: boundary of EC command
         boundary of EC query
  #####: boundary of EC _Qxx evaluation

The following 2 log entries are originally logged using pr_info() in order
to be used as the boot/suspend/resume log entries for the EC device, this
patch also restores them to pr_info() logging level:
 ACPI : EC: EC started
 ACPI : EC: EC stopped

In this patch, one log entry around "Polling quirk" is converted into
ec_dbg_raw() which doesn't contain the boundary marker.

Signed-off-by: Lv Zheng 
Signed-off-by: Rafael J. Wysocki

ACPI / EC: Remove non-standard log emphasis

2015-02-17T17:27:59+00:00

Remove unusual pr_info() visual emphasis introduced in ad479e7f47ca
"ACPI / EC: Introduce STARTED/STOPPED flags to replace BLOCKED flag".

Signed-off-by: Scot Doyle 
[ rjw: Change pr_info() to pr_debug() too in those places. ]
Signed-off-by: Rafael J. Wysocki

Revert "ACPI / EC: Add query flushing support"

2015-02-11T16:35:05+00:00

Revert commit f252cb09e1cb (ACPI / EC: Add query flushing support),
because it breaks system suspend on Acer Aspire S5.  The machine
just hangs solid at the last stage of suspend (after taking non-boot
CPUs offline).

Signed-off-by: Rafael J. Wysocki

Revert "ACPI / EC: Add GPE reference counting debugging messages"

2015-02-11T16:33:23+00:00

Revert commit b5bca896ef3c (ACPI / EC: Add GPE reference counting
debugging messages), because it depends on commit f252cb09e1cb
(ACPI / EC: Add query flushing support) which breaks system suspend
on Acer Aspire S5 and needs to be reverted.

Signed-off-by: Rafael J. Wysocki

ACPI / EC: Add GPE reference counting debugging messages

2015-02-06T14:48:10+00:00

This patch enhances debugging with the GPE reference count messages added.
No functional changes.

Signed-off-by: Lv Zheng 
Signed-off-by: Rafael J. Wysocki

ACPI / EC: Add query flushing support

2015-02-06T14:48:10+00:00

This patch implementes the QR_EC flushing support.

Grace periods are implemented from the detection of an SCI_EVT to the
submission/completion of the QR_EC transaction. During this period, all
EC command transactions are allowed to be submitted.

Note that query periods and event periods are intentionally distiguished to
allow further improvements.
1. Query period: from the detection of an SCI_EVT to the sumission of the
   QR_EC command. This period is used for storming prevention, as currently
   QR_EC is deferred to a work queue rather than directly issued from the
   IRQ context even there is no other transactions pending, so malicous
   SCI_EVT GPE can act like "level triggered" to trigger a GPE storm. We
   need to be prepared for this. And in the future, we may change it to be
   a part of the advance_transaction() where we will try QR_EC submission
   in appropriate positions to avoid such GPE storming.
2. Event period: from the detection of an SCI_EVT to the completion of the
   QR_EC command. We may extend it to the completion of _Qxx evaluation.
   This is actually a grace period for event flushing, but we only flush
   queries due to the reason stated in known issue 1. That's also why we
   use EC_FLAGS_EVENT_xxx. During this period, QR_EC transactions need to
   pass the flushable submission check.

In this patch, the following flags are implemented:
1. EC_FLAGS_EVENT_ENABLED: this is derived from the old
   EC_FLAGS_QUERY_PENDING flag which can block SCI_EVT handlings.
   With this flag, the logics implemented by the original flag are
   extended:
   1. Old logic: unless both of the flags are set, the event poller will
                 not be scheduled, and
   2. New logic: as soon as both of the flags are set, the evet poller will
                 be scheduled.
2. EC_FLAGS_EVENT_DETECTED: this is also derived from the old
   EC_FLAGS_QUERY_PENDING flag which can block SCI_EVT detection. It thus
   can be used to indicate the storming prevention period for query
   submission.
   acpi_ec_submit_request()/acpi_ec_complete_request() are invoked to
   implement this period so that acpi_set_gpe() can be invoked under the
   "reference count > 0" condition.
3. EC_FLAGS_EVENT_PENDING: this is newly added to indicate the grace period
   for event flushing (query flushing for now).
   acpi_ec_submit_request()/acpi_ec_complete_request() are invoked to
   implement this period so that the flushing process can wait until the
   event handling (query transaction for now) to be completed.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=82611
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77431
Signed-off-by: Lv Zheng 
Tested-by: Ortwin Glück 
Signed-off-by: Rafael J. Wysocki

ACPI / EC: Refine command storm prevention support

2015-02-06T14:48:09+00:00

This patch refines EC command storm prevention support.

Current command storming code is wrong, when the storming condition is
detected, it only flags the condition without doing anything for the
current command but performing storming prevention for the follow-up
commands. So:
1. The first command which suffers from the storming still suffers from
   storming.
2. The follow-up commands which may not suffer from the storming are
   unconditionally forced into the storming prevention mode.
Ideally, we should only enable storm prevention immediately after detection
for the current command so that the next command can try the
power/performance efficient interrupt mode again.

This patch improves the command storm prevention by disabling GPE right
after the detection and re-enabling it right before completing the command
transaction using the GPE storming prevention APIs. This thus deploys the
following GPE handling model:
1. acpi_enable_gpe()/acpi_disable_gpe() for reference count changes:
   This set of APIs are used for EC usage reference counting.
2. acpi_set_gpe(ACPI_GPE_ENABLE)/acpi_set_gpe(ACPI_GPE_DISABLE):
   This set of APIs are used for preventing GPE storm. They must be invoked
   when the reference count > 0.
   Note that as the storming prevention should always happen when there is
   an outstanding request, or GPE enabling value will be messed up by the
   races. This patch also adds BUG_ON() to enforces this rule to prevent
   future bugs.

The msleep(1) used after completing a transaction is useless now as this
sounds like a guard time only useful for platforms that need the
EC_FLAGS_MSI quirks while we have fixed GPE race issues using the previous
raw handler mode enabling. It is kept to avoid regressions. A seperate
patch which deletes EC_FLAGS_MSI quirks should take care of deleting it.

Signed-off-by: Lv Zheng 
Signed-off-by: Rafael J. Wysocki