From 37ab3e0d55e3ff3932509bfd2f2625c138b18866 Mon Sep 17 00:00:00 2001 From: Takashi Yano Date: Sun, 1 Sep 2024 04:31:03 +0900 Subject: [PATCH] Cygwin: pipe: Fix a regression that raw_write() slows down After the commit 7f3c22532577, writing to pipe extremely slows down. This is because cygwait(select_sem, 10, cw_cancel) is called even when write operation is already completed. With this patch, the cygwait() is called only if the write operation is not completed. Addresses: https://cygwin.com/pipermail/cygwin/2024-August/256398.html Fixes: 7f3c22532577 ("Cygwin: pipe: handle signals explicitely in raw_write") Reported-by: Jim Reisert AD1C Reviewed-by: Corinna Vinschen Signed-off-by: Takashi Yano (cherry picked from commit f78009cb1ccf84cc343cf2441c76196461d87532) --- winsup/cygwin/fhandler/pipe.cc | 6 ++++-- winsup/cygwin/release/3.5.5 | 3 +++ 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/winsup/cygwin/fhandler/pipe.cc b/winsup/cygwin/fhandler/pipe.cc index 6658a23e7f..997346877d 100644 --- a/winsup/cygwin/fhandler/pipe.cc +++ b/winsup/cygwin/fhandler/pipe.cc @@ -503,8 +503,9 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len) raise (SIGPIPE); goto out; } - else - cygwait (select_sem, 10, cw_cancel); + /* Break out on completion */ + if (waitret == WAIT_OBJECT_0) + break; /* If we got a timeout in the blocking case, and we already did a short write, we got a signal in the previous loop. */ if (waitret == WAIT_TIMEOUT && short_write_once) @@ -512,6 +513,7 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len) waitret = WAIT_SIGNALED; break; } + cygwait (select_sem, 10, cw_cancel); } /* Loop in case of blocking write or SA_RESTART */ while (waitret == WAIT_TIMEOUT || waitret == WAIT_SIGNALED); diff --git a/winsup/cygwin/release/3.5.5 b/winsup/cygwin/release/3.5.5 index a98687c26e..904119a387 100644 --- a/winsup/cygwin/release/3.5.5 +++ b/winsup/cygwin/release/3.5.5 @@ -4,3 +4,6 @@ Fixes: - Fix undesired behaviour of console master thread in win32-input-mode which is supported by Windows Termainal. Addresses: https://cygwin.com/pipermail/cygwin/2024-August/256380.html + +- Fix a regression in 3.5.4 that writing to pipe extremely slows down. + Addresses: https://cygwin.com/pipermail/cygwin/2024-August/256398.html