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* [newlib-cygwin/cygwin-3_3-branch] Cygwin: pty: Prevent deadlock on echo output.
@ 2022-02-13 15:17 Takashi Yano
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From: Takashi Yano @ 2022-02-13 15:17 UTC (permalink / raw)
To: cygwin-cvs
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=c00d44595801b98848bc27b3bf30b0b390df9e42
commit c00d44595801b98848bc27b3bf30b0b390df9e42
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date: Thu Feb 10 17:22:11 2022 +0900
Cygwin: pty: Prevent deadlock on echo output.
- If the slave process writes a lot of text output, doecho() can
cause deadlock. This is because output_mutex is held in slave::
write() and if WriteFile() is blocked due to pipe full, doecho()
tries to acquire output_mutex and gets into deadlock. With this
patch, the deadlock is prevented on the sacrifice of atomicity
of doecho().
Diff:
---
winsup/cygwin/fhandler_tty.cc | 2 --
1 file changed, 2 deletions(-)
diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index 7bef6958c..7e065c46a 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -496,11 +496,9 @@ void
fhandler_pty_master::doecho (const void *str, DWORD len)
{
ssize_t towrite = len;
- acquire_output_mutex (mutex_timeout);
if (!process_opost_output (echo_w, str, towrite, true,
get_ttyp (), is_nonblocking ()))
termios_printf ("Write to echo pipe failed, %E");
- release_output_mutex ();
}
int
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2022-02-13 15:17 [newlib-cygwin/cygwin-3_3-branch] Cygwin: pty: Prevent deadlock on echo output Takashi Yano
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