Patch "scripts: handle BrokenPipeError for python scripts" has been added to the 6.1-stable tree

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This is a note to let you know that I've just added the patch titled

    scripts: handle BrokenPipeError for python scripts

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     scripts-handle-brokenpipeerror-for-python-scripts.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit fa84b491e467a8b6bab70f2e44de4263be45abab
Author: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Date:   Thu Jan 12 11:30:06 2023 +0900

    scripts: handle BrokenPipeError for python scripts
    
    [ Upstream commit 87c7ee67deb7fce9951a5f9d80641138694aad17 ]
    
    In the follow-up of commit fb3041d61f68 ("kbuild: fix SIGPIPE error
    message for AR=gcc-ar and AR=llvm-ar"), Kees Cook pointed out that
    tools should _not_ catch their own SIGPIPEs [1] [2].
    
    Based on his feedback, LLVM was fixed [3].
    
    However, Python's default behavior is to show noisy bracktrace when
    SIGPIPE is sent. So, scripts written in Python are basically in the
    same situation as the buggy llvm tools.
    
    Example:
    
      $ make -s allnoconfig
      $ make -s allmodconfig
      $ scripts/diffconfig .config.old .config | head -n1
      -ALIX n
      Traceback (most recent call last):
        File "/home/masahiro/linux/scripts/diffconfig", line 132, in <module>
          main()
        File "/home/masahiro/linux/scripts/diffconfig", line 130, in main
          print_config("+", config, None, b[config])
        File "/home/masahiro/linux/scripts/diffconfig", line 64, in print_config
          print("+%s %s" % (config, new_value))
      BrokenPipeError: [Errno 32] Broken pipe
    
    Python documentation [4] notes how to make scripts die immediately and
    silently:
    
      """
      Piping output of your program to tools like head(1) will cause a
      SIGPIPE signal to be sent to your process when the receiver of its
      standard output closes early. This results in an exception like
      BrokenPipeError: [Errno 32] Broken pipe. To handle this case,
      wrap your entry point to catch this exception as follows:
    
        import os
        import sys
    
        def main():
            try:
                # simulate large output (your code replaces this loop)
                for x in range(10000):
                    print("y")
                # flush output here to force SIGPIPE to be triggered
                # while inside this try block.
                sys.stdout.flush()
            except BrokenPipeError:
                # Python flushes standard streams on exit; redirect remaining output
                # to devnull to avoid another BrokenPipeError at shutdown
                devnull = os.open(os.devnull, os.O_WRONLY)
                os.dup2(devnull, sys.stdout.fileno())
                sys.exit(1)  # Python exits with error code 1 on EPIPE
    
        if __name__ == '__main__':
            main()
    
      Do not set SIGPIPE’s disposition to SIG_DFL in order to avoid
      BrokenPipeError. Doing that would cause your program to exit
      unexpectedly whenever any socket connection is interrupted while
      your program is still writing to it.
      """
    
    Currently, tools/perf/scripts/python/intel-pt-events.py seems to be the
    only script that fixes the issue that way.
    
    tools/perf/scripts/python/compaction-times.py uses another approach
    signal.signal(signal.SIGPIPE, signal.SIG_DFL) but the Python
    documentation clearly says "Don't do it".
    
    I cannot fix all Python scripts since there are so many.
    I fixed some in the scripts/ directory.
    
    [1]: https://lore.kernel.org/all/202211161056.1B9611A@keescook/
    [2]: https://github.com/llvm/llvm-project/issues/59037
    [3]: https://github.com/llvm/llvm-project/commit/4787efa38066adb51e2c049499d25b3610c0877b
    [4]: https://docs.python.org/3/library/signal.html#note-on-sigpipe
    
    Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
    Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
    Reviewed-by: Nicolas Schier <nicolas@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/scripts/checkkconfigsymbols.py b/scripts/checkkconfigsymbols.py
index 217d21abc86e8..36c920e713137 100755
--- a/scripts/checkkconfigsymbols.py
+++ b/scripts/checkkconfigsymbols.py
@@ -115,7 +115,7 @@ def parse_options():
     return args
 
 
-def main():
+def print_undefined_symbols():
     """Main function of this module."""
     args = parse_options()
 
@@ -467,5 +467,16 @@ def parse_kconfig_file(kfile):
     return defined, references
 
 
+def main():
+    try:
+        print_undefined_symbols()
+    except BrokenPipeError:
+        # Python flushes standard streams on exit; redirect remaining output
+        # to devnull to avoid another BrokenPipeError at shutdown
+        devnull = os.open(os.devnull, os.O_WRONLY)
+        os.dup2(devnull, sys.stdout.fileno())
+        sys.exit(1)  # Python exits with error code 1 on EPIPE
+
+
 if __name__ == "__main__":
     main()
diff --git a/scripts/clang-tools/run-clang-tools.py b/scripts/clang-tools/run-clang-tools.py
index 56f2ec8f0f40a..3266708a86586 100755
--- a/scripts/clang-tools/run-clang-tools.py
+++ b/scripts/clang-tools/run-clang-tools.py
@@ -61,14 +61,21 @@ def run_analysis(entry):
 
 
 def main():
-    args = parse_arguments()
+    try:
+        args = parse_arguments()
 
-    lock = multiprocessing.Lock()
-    pool = multiprocessing.Pool(initializer=init, initargs=(lock, args))
-    # Read JSON data into the datastore variable
-    with open(args.path, "r") as f:
-        datastore = json.load(f)
-        pool.map(run_analysis, datastore)
+        lock = multiprocessing.Lock()
+        pool = multiprocessing.Pool(initializer=init, initargs=(lock, args))
+        # Read JSON data into the datastore variable
+        with open(args.path, "r") as f:
+            datastore = json.load(f)
+            pool.map(run_analysis, datastore)
+    except BrokenPipeError:
+        # Python flushes standard streams on exit; redirect remaining output
+        # to devnull to avoid another BrokenPipeError at shutdown
+        devnull = os.open(os.devnull, os.O_WRONLY)
+        os.dup2(devnull, sys.stdout.fileno())
+        sys.exit(1)  # Python exits with error code 1 on EPIPE
 
 
 if __name__ == "__main__":
diff --git a/scripts/diffconfig b/scripts/diffconfig
index d5da5fa05d1d3..43f0f3d273ae7 100755
--- a/scripts/diffconfig
+++ b/scripts/diffconfig
@@ -65,7 +65,7 @@ def print_config(op, config, value, new_value):
         else:
             print(" %s %s -> %s" % (config, value, new_value))
 
-def main():
+def show_diff():
     global merge_style
 
     # parse command line args
@@ -129,4 +129,16 @@ def main():
     for config in new:
         print_config("+", config, None, b[config])
 
-main()
+def main():
+    try:
+        show_diff()
+    except BrokenPipeError:
+        # Python flushes standard streams on exit; redirect remaining output
+        # to devnull to avoid another BrokenPipeError at shutdown
+        devnull = os.open(os.devnull, os.O_WRONLY)
+        os.dup2(devnull, sys.stdout.fileno())
+        sys.exit(1)  # Python exits with error code 1 on EPIPE
+
+
+if __name__ == '__main__':
+    main()



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