> -----Original Message----- > From: Guenter Roeck [mailto:linux@xxxxxxxxxxxx] > Sent: Wednesday, April 12, 2017 2:23 PM > To: Moore, Robert <robert.moore@xxxxxxxxx> > Cc: Zheng, Lv <lv.zheng@xxxxxxxxx>; Wysocki, Rafael J > <rafael.j.wysocki@xxxxxxxxx>; Len Brown <lenb@xxxxxxxxxx>; linux- > acpi@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] ACPICA: Export mutex functions > > On Wed, Apr 12, 2017 at 03:29:55PM +0000, Moore, Robert wrote: > > The ACPICA mutex functions are based on the host OS functions, so they > don't really buy you anything. You should just use the native Linux > functions. > > > > You mean they don't really acquire the requested ACPI mutex, and the > underlying DSDT which declares and uses the mutex just ignores if the > mutex was acquired by acpi_acquire_mutex() ? > [Moore, Robert] OK, I understand now. Yes, these mutex interfaces are in fact intended for the purpose you mention: * FUNCTION: AcpiAcquireMutex * * PARAMETERS: Handle - Mutex or prefix handle (optional) * Pathname - Mutex pathname (optional) * Timeout - Max time to wait for the lock (millisec) * * RETURN: Status * * DESCRIPTION: Acquire an AML mutex. This is a device driver interface to * AML mutex objects, and allows for transaction locking between * drivers and AML code. The mutex node is pointed to by * Handle:Pathname. Either Handle or Pathname can be NULL, but * not both. And yes, both the acquire and release interfaces should be exported. > To clarify: You are saying that code such as > > acpi_status status; > > status = acpi_acquire_mutex(NULL, "\\_SB.PCI0.SBRG.SIO1.MUT0", > 0x10); > if (ACPI_FAILURE(status)) { > pr_err("Failed to acquire ACPI mutex\n"); > return -EBUSY; > } > ... > > when used in conjunction with > > ... > Mutex (MUT0, 0x00) > Method (ENFG, 1, NotSerialized) > { > Acquire (MUT0, 0x0FFF) > ... > } > > doesn't really provide exclusive access to the resource(s) protected by > MUT0, even if acpi_acquire_mutex() returns ACPI_SUCCESS ? > > Outch. Really ? > > Thanks, > Guenter > > > > > > -----Original Message----- > > > From: Guenter Roeck [mailto:linux@xxxxxxxxxxxx] > > > Sent: Wednesday, April 12, 2017 8:13 AM > > > To: Moore, Robert <robert.moore@xxxxxxxxx>; Zheng, Lv > > > <lv.zheng@xxxxxxxxx>; Wysocki, Rafael J > > > <rafael.j.wysocki@xxxxxxxxx>; Len Brown <lenb@xxxxxxxxxx> > > > Cc: linux-acpi@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx; linux- > > > kernel@xxxxxxxxxxxxxxx; Guenter Roeck <linux@xxxxxxxxxxxx> > > > Subject: [PATCH] ACPICA: Export mutex functions > > > > > > Mutex functions may be needed by drivers. Examples are accesses to > > > Super-IO SIO registers (0x2e/0x2f or 0x4e/0x4f) or Super-IO > > > environmental monitor registers, both which may also be accessed > > > through DSDT. > > > > > > Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> > > > --- > > > drivers/acpi/acpica/utxfmutex.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/drivers/acpi/acpica/utxfmutex.c > > > b/drivers/acpi/acpica/utxfmutex.c index c016211c35ae..5d20581f4b2f > > > 100644 > > > --- a/drivers/acpi/acpica/utxfmutex.c > > > +++ b/drivers/acpi/acpica/utxfmutex.c > > > @@ -150,6 +150,7 @@ acpi_acquire_mutex(acpi_handle handle, > > > acpi_string pathname, u16 timeout) > > > status = acpi_os_acquire_mutex(mutex_obj->mutex.os_mutex, timeout); > > > return (status); > > > } > > > +ACPI_EXPORT_SYMBOL(acpi_acquire_mutex) > > > > > > > > > /******************************************************************* > > > **** > > > ******** > > > * > > > @@ -185,3 +186,4 @@ acpi_status acpi_release_mutex(acpi_handle > > > handle, acpi_string pathname) > > > acpi_os_release_mutex(mutex_obj->mutex.os_mutex); > > > return (AE_OK); > > > } > > > +ACPI_EXPORT_SYMBOL(acpi_release_mutex) > > > -- > > > 2.7.4 > > -- 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
