From: Alexey Starikovskiy <alexey.y.starikovskiy@xxxxxxxxx> Delay the read of the EC status register until after the event that caused it occurs -- otherwise it is possible to read and act on stale status that was associated with the previous event. Do this with a perpetually incrementing "event_count" to detect when a new event occurs and it is safe to read status. There is no workaround for polling mode -- it is inherently exposed to reading and acting on stale status, since it doesn't have an interrupt to tell it the event completed. http://bugzilla.kernel.org/show_bug.cgi?id=8110 Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@xxxxxxxxx> Signed-off-by: Len Brown <len.brown@xxxxxxxxx> --- drivers/acpi/ec.c | 40 +++++++++++++++++++++++----------------- 1 files changed, 23 insertions(+), 17 deletions(-) diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index ab68883..1e525dd 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -100,6 +100,7 @@ static struct acpi_ec { unsigned long global_lock; struct mutex lock; atomic_t query_pending; + atomic_t event_count; atomic_t leaving_burst; /* 0 : No, 1 : Yes, 2: abort */ wait_queue_head_t wait; } *ec_ecdt; @@ -131,10 +132,12 @@ static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data) outb(data, ec->data_addr); } -static inline int acpi_ec_check_status(struct acpi_ec *ec, enum ec_event event) +static inline int acpi_ec_check_status(struct acpi_ec *ec, enum ec_event event, + unsigned old_count) { u8 status = acpi_ec_read_status(ec); - + if (old_count == atomic_read(&ec->event_count)) + return 0; if (event == ACPI_EC_EVENT_OBF_1) { if (status & ACPI_EC_FLAG_OBF) return 1; @@ -146,19 +149,19 @@ static inline int acpi_ec_check_status(struct acpi_ec *ec, enum ec_event event) return 0; } -static int acpi_ec_wait(struct acpi_ec *ec, enum ec_event event) +static int acpi_ec_wait(struct acpi_ec *ec, enum ec_event event, unsigned count) { if (acpi_ec_mode == EC_POLL) { unsigned long delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY); while (time_before(jiffies, delay)) { - if (acpi_ec_check_status(ec, event)) + if (acpi_ec_check_status(ec, event, 0)) return 0; } } else { if (wait_event_timeout(ec->wait, - acpi_ec_check_status(ec, event), + acpi_ec_check_status(ec, event, count), msecs_to_jiffies(ACPI_EC_DELAY)) || - acpi_ec_check_status(ec, event)) { + acpi_ec_check_status(ec, event, 0)) { return 0; } else { printk(KERN_ERR PREFIX "acpi_ec_wait timeout," @@ -225,21 +228,22 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, u8 command, u8 * rdata, unsigned rdata_len) { int result = 0; - + unsigned count = atomic_read(&ec->event_count); acpi_ec_write_cmd(ec, command); for (; wdata_len > 0; --wdata_len) { - result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0); + result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, count); if (result) { printk(KERN_ERR PREFIX "write_cmd timeout, command = %d\n", command); goto end; } + count = atomic_read(&ec->event_count); acpi_ec_write_data(ec, *(wdata++)); } if (!rdata_len) { - result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0); + result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, count); if (result) { printk(KERN_ERR PREFIX "finish-write timeout, command = %d\n", command); @@ -250,13 +254,13 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, u8 command, } for (; rdata_len > 0; --rdata_len) { - result = acpi_ec_wait(ec, ACPI_EC_EVENT_OBF_1); + result = acpi_ec_wait(ec, ACPI_EC_EVENT_OBF_1, count); if (result) { printk(KERN_ERR PREFIX "read timeout, command = %d\n", command); goto end; } - + count = atomic_read(&ec->event_count); *(rdata++) = acpi_ec_read_data(ec); } end: @@ -288,7 +292,7 @@ static int acpi_ec_transaction(struct acpi_ec *ec, u8 command, /* Make sure GPE is enabled before doing transaction */ acpi_enable_gpe(NULL, ec->gpe, ACPI_NOT_ISR); - status = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0); + status = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, 0); if (status) { printk(KERN_DEBUG PREFIX "input buffer is not empty, aborting transaction\n"); @@ -369,8 +373,8 @@ int ec_write(u8 addr, u8 val) EXPORT_SYMBOL(ec_write); int ec_transaction(u8 command, - const u8 * wdata, unsigned wdata_len, - u8 * rdata, unsigned rdata_len) + const u8 * wdata, unsigned wdata_len, + u8 * rdata, unsigned rdata_len) { struct acpi_ec *ec; @@ -435,7 +439,7 @@ static u32 acpi_ec_gpe_handler(void *data) acpi_status status = AE_OK; u8 value; struct acpi_ec *ec = (struct acpi_ec *)data; - + atomic_inc(&ec->event_count); if (acpi_ec_mode == EC_INTR) { wake_up(&ec->wait); } @@ -633,6 +637,7 @@ static int acpi_ec_add(struct acpi_device *device) ec->uid = -1; mutex_init(&ec->lock); atomic_set(&ec->query_pending, 0); + atomic_set(&ec->event_count, 1); if (acpi_ec_mode == EC_INTR) { atomic_set(&ec->leaving_burst, 1); init_waitqueue_head(&ec->wait); @@ -807,6 +812,7 @@ acpi_fake_ecdt_callback(acpi_handle handle, acpi_status status; mutex_init(&ec_ecdt->lock); + atomic_set(&ec->event_count, 1); if (acpi_ec_mode == EC_INTR) { init_waitqueue_head(&ec_ecdt->wait); } @@ -888,6 +894,7 @@ static int __init acpi_ec_get_real_ecdt(void) return -ENOMEM; mutex_init(&ec_ecdt->lock); + atomic_set(&ec_ecdt->event_count, 1); if (acpi_ec_mode == EC_INTR) { init_waitqueue_head(&ec_ecdt->wait); } @@ -1016,8 +1023,7 @@ static int __init acpi_ec_set_intr_mode(char *str) acpi_ec_mode = EC_POLL; } acpi_ec_driver.ops.add = acpi_ec_add; - printk(KERN_NOTICE PREFIX "%s mode.\n", - intr ? "interrupt" : "polling"); + printk(KERN_NOTICE PREFIX "%s mode.\n", intr ? "interrupt" : "polling"); return 1; } -- 1.5.0.3.310.g05ef5 - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
