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authorLv Zheng <lv.zheng@intel.com>2016-08-03 04:00:14 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-08-04 03:07:53 +0300
commite1191bd4f62d9086a1a47adc286e7fcffc1fa55c (patch)
tree085e46a8bb91d7d82df91955a4929ffb60599eb9 /drivers/acpi/ec.c
parentbc539567ab521ff10c6060ccb6f7665561551f72 (diff)
downloadlinux-e1191bd4f62d9086a1a47adc286e7fcffc1fa55c.tar.xz
ACPI / EC: Work around method reentrancy limit in ACPICA for _Qxx
A regression is caused by the following commit: Commit: 02b771b64b73226052d6e731a0987db3b47281e9 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: 02b771b64b73 (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>
Diffstat (limited to 'drivers/acpi/ec.c')
-rw-r--r--drivers/acpi/ec.c41
1 files changed, 37 insertions, 4 deletions
diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index b1050a0c10fb..13d1b9487990 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -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 */