ACPI: Add acpi_handle_<level>() interfaces
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>
diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
index 462f7e3..74437130 100644
--- a/drivers/acpi/utils.c
+++ b/drivers/acpi/utils.c
@@ -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 @@
#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);