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ACPI: Add acpi_handle_<level>() interfaces

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This patch introduces acpi_handle_<level>(), where <level> is
a kernel message level such as err/warn/info, to support improved
logging messages for ACPI, esp. hot-plug operations.
acpi_handle_<level>() appends "ACPI" prefix and ACPI object path
to the messages.  This improves diagnosis of hotplug operations
since an error message in a log file identifies an object that
caused an issue.  This interface acquires the global namespace
mutex to obtain an object path.  In interrupt context, it shows
the object path as <n/a>.

acpi_handle_<level>() takes acpi_handle as an argument, which is
passed to ACPI hotplug notify handlers from the ACPICA.  Therefore,
it is always available unlike other kernel objects, such as device.

For example:
  acpi_handle_err(handle, "Device don't exist, dropping EJECT\n");
logs an error message like this at KERN_ERR.
  ACPI: \_SB_.SCK4.CPU4: Device don't exist, dropping EJECT

ACPI hot-plug drivers can use acpi_handle_<level>() when they need
to identify a target ACPI object path in their messages, such as
error cases.  The usage model is similar to dev_<level>().
acpi_handle_<level>() can be used when a device is not created or
is invalid during hot-plug operations.  ACPI object path is also
consistent on the platform, unlike device name that gets incremented
over hotplug operations.

ACPI drivers should use dev_<level>() when a device object is valid.
Device name provides more user friendly information, and avoids
acquiring the global ACPI namespace mutex.  ACPI drivers also
continue to use pr_<level>() when they do not need to specify device
information, such as boot-up messages.

Note: ACPI_[WARNING|INFO|ERROR]() are intended for the ACPICA and
are not associated with the kernel message level.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Tested-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Toshi Kani
2012-11-21 01:36:28 +00:00
committed by Rafael J. Wysocki
parent b59bc2fbb4
commit fbfddae696
2 changed files with 81 additions and 0 deletions
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38
drivers/acpi/utils.c
View File

@@ -28,6 +28,8 @@
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/hardirq.h>
#include <linux/acpi.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
@@ -457,3 +459,39 @@ acpi_evaluate_hotplug_ost(acpi_handle handle, u32 source_event,
#endif
}
EXPORT_SYMBOL(acpi_evaluate_hotplug_ost);
/**
* acpi_handle_printk: Print message with ACPI prefix and object path
*
* This function is called through acpi_handle_<level> macros and prints
* a message with ACPI prefix and object path. This function acquires
* the global namespace mutex to obtain an object path. In interrupt
* context, it shows the object path as <n/a>.
*/
void
acpi_handle_printk(const char *level, acpi_handle handle, const char *fmt, ...)
{
struct va_format vaf;
va_list args;
struct acpi_buffer buffer = {
.length = ACPI_ALLOCATE_BUFFER,
.pointer = NULL
};
const char *path;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
if (in_interrupt() ||
acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer) != AE_OK)
path = "<n/a>";
else
path = buffer.pointer;
printk("%sACPI: %s: %pV", level, path, &vaf);
va_end(args);
kfree(buffer.pointer);
}
EXPORT_SYMBOL(acpi_handle_printk);