From: Lv Zheng <lv.zheng@xxxxxxxxx> This patch has been added to the 3.12 stable tree. If you have any objections, please let us know. =============== commit c0d653412fc8450370167a3268b78fc772ff9c87 upstream. There is a race condition in ec_transaction_completed(). When ec_transaction_completed() is called in the GPE handler, it could return true because of (ec->curr == NULL). Then the wake_up() invocation could complete the next command unexpectedly since there is no lock between the 2 invocations. With the previous cleanup, the IBF=0 waiter race need not be handled any more. It's now safe to return a flag from advance_condition() to indicate the requirement of wakeup, the flag is returned from a locked context. The ec_transaction_completed() is now only invoked by the ec_poll() where the ec->curr is ensured to be different from NULL. After cleaning up, the EVT_SCI=1 check should be moved out of the wakeup condition so that an EVT_SCI raised with (ec->curr == NULL) can trigger a QR_SC command. Link: https://bugzilla.kernel.org/show_bug.cgi?id=70891 Link: https://bugzilla.kernel.org/show_bug.cgi?id=63931 Link: https://bugzilla.kernel.org/show_bug.cgi?id=59911 Reported-and-tested-by: Gareth Williams <gareth@xxxxxxxxxxxxxxxxxxxx> Reported-and-tested-by: Hans de Goede <jwrdegoede@xxxxxxxxxxxxxxxxx> Reported-by: Barton Xu <tank.xuhan@xxxxxxxxx> Tested-by: Steffen Weber <steffen.weber@xxxxxxxxx> Tested-by: Arthur Chen <axchen@xxxxxxxxxx> Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- drivers/acpi/ec.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index 7b52a724a0dd..7171d52e12ca 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -165,16 +165,17 @@ static int ec_transaction_completed(struct acpi_ec *ec) unsigned long flags; int ret = 0; spin_lock_irqsave(&ec->lock, flags); - if (!ec->curr || (ec->curr->flags & ACPI_EC_COMMAND_COMPLETE)) + if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_COMPLETE)) ret = 1; spin_unlock_irqrestore(&ec->lock, flags); return ret; } -static void advance_transaction(struct acpi_ec *ec) +static bool advance_transaction(struct acpi_ec *ec) { struct transaction *t; u8 status; + bool wakeup = false; pr_debug("===== %s =====\n", in_interrupt() ? "IRQ" : "TASK"); status = acpi_ec_read_status(ec); @@ -190,21 +191,25 @@ static void advance_transaction(struct acpi_ec *ec) } else if (t->rlen > t->ri) { if ((status & ACPI_EC_FLAG_OBF) == 1) { t->rdata[t->ri++] = acpi_ec_read_data(ec); - if (t->rlen == t->ri) + if (t->rlen == t->ri) { t->flags |= ACPI_EC_COMMAND_COMPLETE; + wakeup = true; + } } else goto err; } else if (t->wlen == t->wi && - (status & ACPI_EC_FLAG_IBF) == 0) + (status & ACPI_EC_FLAG_IBF) == 0) { t->flags |= ACPI_EC_COMMAND_COMPLETE; - return; + wakeup = true; + } + return wakeup; } else { if ((status & ACPI_EC_FLAG_IBF) == 0) { acpi_ec_write_cmd(ec, t->command); t->flags |= ACPI_EC_COMMAND_POLL; } else goto err; - return; + return wakeup; } err: /* @@ -215,13 +220,14 @@ err: if (in_interrupt() && t) ++t->irq_count; } + return wakeup; } static void start_transaction(struct acpi_ec *ec) { ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0; ec->curr->flags = 0; - advance_transaction(ec); + (void)advance_transaction(ec); } static int acpi_ec_sync_query(struct acpi_ec *ec, u8 *data); @@ -255,7 +261,7 @@ static int ec_poll(struct acpi_ec *ec) return 0; } spin_lock_irqsave(&ec->lock, flags); - advance_transaction(ec); + (void)advance_transaction(ec); spin_unlock_irqrestore(&ec->lock, flags); } while (time_before(jiffies, delay)); pr_debug(PREFIX "controller reset, restart transaction\n"); @@ -654,12 +660,10 @@ static u32 acpi_ec_gpe_handler(acpi_handle gpe_device, struct acpi_ec *ec = data; spin_lock_irqsave(&ec->lock, flags); - advance_transaction(ec); - spin_unlock_irqrestore(&ec->lock, flags); - if (ec_transaction_completed(ec)) { + if (advance_transaction(ec)) wake_up(&ec->wait); - ec_check_sci(ec, acpi_ec_read_status(ec)); - } + spin_unlock_irqrestore(&ec->lock, flags); + ec_check_sci(ec, acpi_ec_read_status(ec)); return ACPI_INTERRUPT_HANDLED | ACPI_REENABLE_GPE; } -- 2.0.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html