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commit de19e5c3c51fdb1ff20d0f61d099db902ff7494b upstream. trigger_on() means that the trigger is available but not ready, however trigger_on() was making it ready. That can segfault if the signal comes before trigger_ready(). e.g. (USR2 signal delivery not shown) $ perf record -e intel_pt//u -S sleep 1 perf: Segmentation fault Obtained 16 stack frames. /home/ahunter/bin/perf(sighandler_dump_stack+0x40) [0x4ec550] /lib/x86_64-linux-gnu/libc.so.6(+0x36caf) [0x7fa76411acaf] /home/ahunter/bin/perf(perf_evsel__disable+0x26) [0x4b9dd6] /home/ahunter/bin/perf() [0x43a45b] /lib/x86_64-linux-gnu/libc.so.6(+0x36caf) [0x7fa76411acaf] /lib/x86_64-linux-gnu/libc.so.6(__xstat64+0x15) [0x7fa7641d2cc5] /home/ahunter/bin/perf() [0x4ec6c9] /home/ahunter/bin/perf() [0x4ec73b] /home/ahunter/bin/perf() [0x4ec73b] /home/ahunter/bin/perf() [0x4ec73b] /home/ahunter/bin/perf() [0x4eca15] /home/ahunter/bin/perf(machine__create_kernel_maps+0x257) [0x4f0b77] /home/ahunter/bin/perf(perf_session__new+0xc0) [0x4f86f0] /home/ahunter/bin/perf(cmd_record+0x722) [0x43c132] /home/ahunter/bin/perf() [0x4a11ae] /home/ahunter/bin/perf(main+0x5d4) [0x427fb4] Note, for testing purposes, this is hard to hit unless you add some sleep() in builtin-record.c before record__open(). Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Cc: stable@vger.kernel.org Fixes: 3dcc4436fa6f ("perf tools: Introduce trigger class") Link: http://lkml.kernel.org/r/1519807144-30694-1-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.