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authorCarlos O'Donell <carlos@redhat.com>2014-11-06 15:58:52 -0500
committerCarlos O'Donell <carlos@redhat.com>2014-11-06 15:58:52 -0500
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manual/llio.texi: Comment on write atomicity.
We add Linux-realted comments about the atomicity of write with respect to file offsets. As of Linux 3.14 the file offset update is atomic. That means that multiple threads calling the write syscall can not possibly get the same file offset. Therefore the writes should not overlap and data should not be lost as is required by POSIX.
Diffstat (limited to 'manual')
-rw-r--r--manual/llio.texi5
1 files changed, 5 insertions, 0 deletions
diff --git a/manual/llio.texi b/manual/llio.texi
index 393ddf3..4f3fada 100644
--- a/manual/llio.texi
+++ b/manual/llio.texi
@@ -491,6 +491,11 @@ When the source file is compiled with @code{_FILE_OFFSET_BITS == 64} on a
@c
@c So we mark it thread safe, it doesn't blow up, but you might loose
@c data, and we don't strictly meet the POSIX requirements.
+@c
+@c The fix for file offsets racing was merged in 3.14, the commits were:
+@c 9c225f2655e36a470c4f58dbbc99244c5fc7f2d4, and
+@c d7a15f8d0777955986a2ab00ab181795cab14b01. Therefore after Linux 3.14 you
+@c should get mostly MT-safe writes.
The @code{write} function writes up to @var{size} bytes from
@var{buffer} to the file with descriptor @var{filedes}. The data in
@var{buffer} is not necessarily a character string and a null character is