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757d914007
linux/kernel/trace
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Steven Rostedt (VMware) 757d914007 tracing/blktrace: Fix to allow setting same value 
Masami Hiramatsu reported:

  Current trace-enable attribute in sysfs returns an error
  if user writes the same setting value as current one,
  e.g.

    # cat /sys/block/sda/trace/enable
    0
    # echo 0 > /sys/block/sda/trace/enable
    bash: echo: write error: Invalid argument
    # echo 1 > /sys/block/sda/trace/enable
    # echo 1 > /sys/block/sda/trace/enable
    bash: echo: write error: Device or resource busy

  But this is not a preferred behavior, it should ignore
  if new setting is same as current one. This fixes the
  problem as below.

    # cat /sys/block/sda/trace/enable
    0
    # echo 0 > /sys/block/sda/trace/enable
    # echo 1 > /sys/block/sda/trace/enable
    # echo 1 > /sys/block/sda/trace/enable

Link: http://lkml.kernel.org/r/20180816103802.08678002@gandalf.local.home

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: cd649b8bb8 ("blktrace: remove sysfs_blk_trace_enable_show/store()")
Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-16 14:13:56 -06:00
..
blktrace.c tracing/blktrace: Fix to allow setting same value 2018-08-16 14:13:56 -06:00
bpf_trace.c bpf: guard bpf_get_current_cgroup_id() with CONFIG_CGROUPS 2018-06-04 21:52:26 +02:00
ftrace.c ftrace: Nuke clear_ftrace_function 2018-07-03 18:33:19 -04:00
Kconfig docs: Fix some broken references 2018-06-15 18:10:01 -03:00
Makefile Tracing updates for 4.15: 2017-11-17 14:58:01 -08:00
power-traces.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ring_buffer_benchmark.c ring-buffer: Have ring_buffer_alloc_read_page() return error on offline CPU 2017-08-02 14:23:02 -04:00
ring_buffer.c ring-buffer: Fix a bunch of typos in comments 2018-06-04 17:28:19 -04:00
rpm-traces.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_benchmark.c rcu: Rename cond_resched_rcu_qs() to cond_resched_tasks_rcu_qs() 2018-05-15 10:27:29 -07:00
trace_benchmark.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_branch.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_clock.c tracing: Hide global trace clock from lockdep 2018-04-06 08:56:52 -04:00
trace_entries.h tracing: Add trigger file for trace_markers tracefs/ftrace/print 2018-05-29 08:28:53 -04:00
trace_event_perf.c perf/core: Fix perf_uprobe_init() 2018-04-10 07:33:10 +02:00
trace_events_filter_test.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_events_filter.c tracing: Make create_filter() code match the comments 2018-07-03 18:14:40 -04:00
trace_events_hist.c tracing: Avoid string overflow 2018-07-03 18:14:39 -04:00
trace_events_trigger.c tracing: Do not reference event data in post call triggers 2018-05-29 08:28:02 -04:00
trace_events.c tracing: Do not show filter file for ftrace internal events 2018-05-29 08:28:46 -04:00
trace_export.c tracing: Add trigger file for trace_markers tracefs/ftrace/print 2018-05-29 08:28:53 -04:00
trace_functions_graph.c tracing: Fix missing return symbol in function_graph output 2018-07-03 18:47:11 -04:00
trace_functions.c tracing: Update stack trace skipping for ORC unwinder 2018-01-23 15:57:00 -05:00
trace_hwlat.c trace: make trace_hwlat timestamp y2038 safe 2017-05-08 17:15:15 -07:00
trace_irqsoff.c tracing: Add support for preempt and irq enable/disable events 2017-10-10 18:58:43 -04:00
trace_kdb.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_kprobe.c tracing/kprobe: Release kprobe print_fmt properly 2018-07-11 15:50:52 -04:00
trace_mmiotrace.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_nop.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_output.c tracing: Reorder display of TGID to be after PID 2018-07-12 19:56:25 -04:00
trace_output.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_printk.c treewide: Align function definition open/close braces 2018-03-26 11:13:09 +02:00
trace_probe.c tracing: probeevent: Fix to support minus offset from symbol 2018-03-23 12:02:37 -04:00
trace_probe.h Merge branch 'perf/urgent' into perf/core 2018-03-29 16:03:48 +02:00
trace_sched_switch.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_sched_wakeup.c Merge branch 'linus' into sched/core, to pick up fixes 2017-11-08 10:17:15 +01:00
trace_selftest_dynamic.c ftrace: Mark function tracer test functions noinline/noclone 2018-01-23 15:57:29 -05:00
trace_selftest.c Tracing updates for 4.15: 2017-11-17 14:58:01 -08:00
trace_seq.c tracing: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:37 -08:00
trace_stack.c tracing: Fix the file mode of stack tracer 2018-05-03 11:58:05 -04:00
trace_stat.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_stat.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace_syscalls.c Tracing updates for 4.15: 2017-11-17 14:58:01 -08:00
trace_uprobe.c bpf: introduce bpf subcommand BPF_TASK_FD_QUERY 2018-05-24 18:18:19 -07:00
trace.c tracing: Reorder display of TGID to be after PID 2018-07-12 19:56:25 -04:00
trace.h tracing: Optimize trace_buffer_iter() logic 2018-07-03 18:23:33 -04:00
tracing_map.c treewide: Use array_size() in vmalloc() 2018-06-12 16:19:22 -07:00
tracing_map.h tracing: Add per-element variable support to tracing_map 2018-03-10 16:05:53 -05:00