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Tom de Vries c4df8ad79c [gdb/build] Workaround tsan select bug
When building gdb with -O0 and -fsanitize-thread, I run into a large number of
timeouts caused by gdb hanging, for instance:
...
(gdb) continue^M
Continuing.^M
[Inferior 1 (process 378) exited normally]^M
FAIL: gdb.multi/stop-all-on-exit.exp: continue until exit (timeout)
...

What happens is the following:
- two inferiors are added, stopped at main
- inferior 1 is setup to exit after 1 second
- inferior 2 is setup to exit after 10 seconds
- the continue command is issued
- because of set schedule-multiple on, both inferiors continue
- the first inferior exits
- gdb sends a SIGSTOP to the second inferior
- the second inferior receives the SIGSTOP, and raises a SIGCHILD
- gdb calls select, and blocks
- the signal arrives, and interrupts select
- ThreadSanitizers signal handler is called, which marks the signal pending
  internally
- select returns -1 with errno == EINTR
- gdb calls select again, and blocks
- gdb hangs, waiting for gdb's sigchild_handler to be called

This is a bug [1] in ThreadSanitizer.  When select is called with
timeout == nullptr, it is blocking but ThreadSanitizer doesn't consider it so,
and consequently doesn't see the need to call sigchild_handler.

Work around this by:
- instead of using the blocking select variant, forcing a small timeout and
- upon timeout calling a function that ThreadSanitizer does consider
  blocking: usleep, forcing sigchild_handler to be called.

Tested on x86_64-linux.

PR build/32295
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32295

[1] https://github.com/google/sanitizers/issues/1813
2024-11-22 12:54:57 +01:00
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gas RISC-V: Support SiFive extensions: xsfvqmaccdod, xsfvqmaccqoq and xsfvfnrclipxfqf 2024-11-22 09:56:54 +08:00
gdb [gdb/build] Workaround tsan select bug 2024-11-22 12:54:57 +01:00
gdbserver gdbserver: pass osabi to GDB in more target descriptions 2024-11-12 12:51:36 +00:00
gdbsupport [gdb] Fix some typos 2024-11-18 09:46:31 +01:00
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		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
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If you are receiving this as part of a GDB release, see the file gdb/README.
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	./configure 
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	CC=gcc ./configure
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	setenv CC gcc
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