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Currently, exception event status can be read from wExceptionEventStatus
attribute (sysfs file attributes/exception_event_status under the UFS host
controller device directory). Polling that attribute to track UFS exception
events is impractical, so add a tracepoint to track exception events for
testing and debugging purposes.
Note, by the time the exception event status is read, the exception event
may have cleared, so the value can be zero - see example below.
Note also, only enabled exception events can be reported. A subsequent
patch adds the ability for users to enable selected exception events via
debugfs.
Example with driver instrumented to enable all exception events:
# echo 1 > /sys/kernel/debug/tracing/events/ufs/ufshcd_exception_event/enable
... do some I/O ...
# cat /sys/kernel/debug/tracing/trace
# tracer: nop
#
# entries-in-buffer/entries-written: 3/3 #P:5
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
kworker/2:2-173 [002] .... 731.486419: ufshcd_exception_event: 0000:00:12.5: status 0x0
kworker/2:2-173 [002] .... 732.608918: ufshcd_exception_event: 0000:00:12.5: status 0x4
kworker/2:2-173 [002] .... 732.609312: ufshcd_exception_event: 0000:00:12.5: status 0x4
Link: https://lore.kernel.org/r/20210209062437.6954-2-adrian.hunter@intel.com
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.