Re: ec locking issue

[Alexey Starikovskiy <alexey.y.starikovskiy@linux.intel.com>]

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Hi,

ec is locked only in acpi_ec_transaction, and it is only once in your 
stack.
I doubt that this patch could change something, but worth a try...
Is bisect finds something?

Regards,
    Alex.
Dominik Brodowski wrote:
> Hi,
>
> Current kernels (e.g. 2.6.20-git-as-of-yesterday) don't boot for me, and
> it seems like ACPI is the cause: the last thing I can see in the log is
>
> swapper/1 is trying to acquire lock
> 	&ec->lock
>
> but task is already holding lock
> 	&ec->lock
>
> Snippets from the call trace:
>
> acpi_ec_transaction
> acpi_ec_read
> acpi_ec_space_handler
> acpi_ev_address_space_dispatch
> acpi_ex_access_region
> acpi_ex_field_datum_
> acpi_ex_extract_from_field
> ...
> acpi_ex_ns_evaluate
> acpi_ev_execute_reg_method
> acpi_ev_reg_run
> acpi_ns_walk_namespace
> acpi_ev_execute_reg_methods
> acpi_install_address_space_handler
> acpi_ec_start
> acpi_start_single_object
> acpi_device_probe
> really_probe
> ...
> bus_add_driver
> ...
> acpi_ec_init
>
>
>
> Ideas? Patches?
>
> Thanks,
> 	Dominik
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diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 743ce27..8f5aaf7 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -280,8 +280,10 @@ static int acpi_ec_transaction(struct ac
 	mutex_lock(&ec->lock);
 	if (ec->global_lock) {
 		status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk);
-		if (ACPI_FAILURE(status))
+		if (ACPI_FAILURE(status)) {
+			mutex_unlock(&ec->lock);
 			return -ENODEV;
+		}
 	}
 
 	/* Make sure GPE is enabled before doing transaction */