Changbin Du de9f498d2b perf trace: Avoid early exit due SIGCHLD from non-workload processes
The function trace__symbols_init() runs "perf-read-vdso32" and that ends up
with a SIGCHLD delivered to 'perf'. And this SIGCHLD make perf exit early.

'perf trace' should exit only if the SIGCHLD is from our workload process.
So let's use sigaction() instead of signal() to match such condition.

Committer notes:

Use memset to zero the 'struct sigaction' variable as the '= { 0 }'
method isn't accepted in many compiler versions, e.g.:

   4    34.02 alpine:3.6                    : FAIL clang version 4.0.0 (tags/RELEASE_400/final)
    builtin-trace.c:4897:35: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces]
            struct sigaction sigchld_act = { 0 };
                                             ^
                                             {}
    builtin-trace.c:4897:37: error: missing field 'sa_mask' initializer [-Werror,-Wmissing-field-initializers]
            struct sigaction sigchld_act = { 0 };
                                               ^
    2 errors generated.
   6    32.60 alpine:3.8                    : FAIL gcc version 6.4.0 (Alpine 6.4.0)
    builtin-trace.c:4897:35: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces]
            struct sigaction sigchld_act = { 0 };
                                             ^
                                             {}
    builtin-trace.c:4897:37: error: missing field 'sa_mask' initializer [-Werror,-Wmissing-field-initializers]
            struct sigaction sigchld_act = { 0 };
                                               ^
    2 errors generated.
   7    34.82 alpine:3.9                    : FAIL gcc version 8.3.0 (Alpine 8.3.0)
    builtin-trace.c:4897:35: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces]
            struct sigaction sigchld_act = { 0 };
                                             ^
                                             {}
    builtin-trace.c:4897:37: error: missing field 'sa_mask' initializer [-Werror,-Wmissing-field-initializers]
            struct sigaction sigchld_act = { 0 };
                                               ^
    2 errors generated.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220208140725.3947-1-changbin.du@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-02-16 13:47:12 -03:00
2022-02-13 12:13:30 -08:00

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.
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