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ACPI / EC: Work around method reentrancy limit in ACPICA for _Qxx 

A regression is caused by the following commit:

  Commit: 02b771b64b
  Subject: ACPI / EC: Fix an issue caused by the serialized _Qxx evaluations

In this commit, using system workqueue causes that the maximum parallel
executions of _Qxx can exceed 255. This violates the method reentrancy
limit in ACPICA and generates the following error log:

  ACPI Error: Method reached maximum reentrancy limit (255) (20150818/dsmethod-341)

This patch creates a seperate workqueue and limits the number of parallel
_Qxx evaluations down to a configurable value (can be tuned against number
of online CPUs).

Since EC events are handled after driver probe, we can create the workqueue
in acpi_ec_init().

Fixes: 02b771b64b (ACPI / EC: Fix an issue caused by the serialized _Qxx evaluations)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=135691
Cc: 4.3+ <stable@vger.kernel.org> # 4.3+
Reported-and-tested-by: Helen Buus <ubuntu@hbuus.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Lv Zheng 2016-08-03 09:00:14 +08:00 committed by Rafael J. Wysocki
parent bc539567ab
commit e1191bd4f6
1 changed files with 37 additions and 4 deletions
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41
drivers/acpi/ec.c
View File

@ -101,6 +101,7 @@ enum ec_command {
#define ACPI_EC_UDELAY_POLL 550 /* Wait 1ms for EC transaction polling */
#define ACPI_EC_CLEAR_MAX 100 /* Maximum number of events to query
* when trying to clear the EC */
#define ACPI_EC_MAX_QUERIES 16 /* Maximum number of parallel queries */
enum {
EC_FLAGS_QUERY_PENDING, /* Query is pending */
@ -121,6 +122,10 @@ static unsigned int ec_delay __read_mostly = ACPI_EC_DELAY;
module_param(ec_delay, uint, 0644);
MODULE_PARM_DESC(ec_delay, "Timeout(ms) waited until an EC command completes");
static unsigned int ec_max_queries __read_mostly = ACPI_EC_MAX_QUERIES;
module_param(ec_max_queries, uint, 0644);
MODULE_PARM_DESC(ec_max_queries, "Maximum parallel _Qxx evaluations");
static bool ec_busy_polling __read_mostly;
module_param(ec_busy_polling, bool, 0644);
MODULE_PARM_DESC(ec_busy_polling, "Use busy polling to advance EC transaction");
@ -174,6 +179,7 @@ static void acpi_ec_event_processor(struct work_struct *work);
struct acpi_ec *boot_ec, *first_ec;
EXPORT_SYMBOL(first_ec);
static struct workqueue_struct *ec_query_wq;
static int EC_FLAGS_CLEAR_ON_RESUME; /* Needs acpi_ec_clear() on boot/resume */
static int EC_FLAGS_QUERY_HANDSHAKE; /* Needs QR_EC issued when SCI_EVT set */
@ -1098,7 +1104,7 @@ static int acpi_ec_query(struct acpi_ec *ec, u8 *data)
* work queue execution.
*/
ec_dbg_evt("Query(0x%02x) scheduled", value);
if (!schedule_work(&q->work)) {
if (!queue_work(ec_query_wq, &q->work)) {
ec_dbg_evt("Query(0x%02x) overlapped", value);
result = -EBUSY;
}
@ -1649,15 +1655,41 @@ static struct acpi_driver acpi_ec_driver = {
},
};
static inline int acpi_ec_query_init(void)
{
if (!ec_query_wq) {
ec_query_wq = alloc_workqueue("kec_query", 0,
ec_max_queries);
if (!ec_query_wq)
return -ENODEV;
}
return 0;
}
static inline void acpi_ec_query_exit(void)
{
if (ec_query_wq) {
destroy_workqueue(ec_query_wq);
ec_query_wq = NULL;
}
}
int __init acpi_ec_init(void)
{
int result = 0;
int result;
/* register workqueue for _Qxx evaluations */
result = acpi_ec_query_init();
if (result)
goto err_exit;
/* Now register the driver for the EC */
result = acpi_bus_register_driver(&acpi_ec_driver);
if (result < 0)
return -ENODEV;
if (result)
goto err_exit;
err_exit:
if (result)
acpi_ec_query_exit();
return result;
}
@ -1667,5 +1699,6 @@ static void __exit acpi_ec_exit(void)
{
acpi_bus_unregister_driver(&acpi_ec_driver);
acpi_ec_query_exit();
}
#endif /* 0 */