From: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: binutils@sourceware.org
Subject: Re: PATCH: PR binutils/12283: bfd/doc doesn't support parallel build
Date: Thu, 02 Dec 2010 18:32:00 -0000 [thread overview]
Message-ID: <20101202183231.GD16143@gmx.de> (raw)
In-Reply-To: <20101202182235.GC16143@gmx.de>
* Ralf Wildenhues wrote on Thu, Dec 02, 2010 at 07:22:35PM CET:
> * Ralf Wildenhues wrote on Thu, Dec 02, 2010 at 07:20:50PM CET:
> > * H.J. Lu wrote on Thu, Dec 02, 2010 at 07:16:07PM CET:
> > > Failure is very random. There is a race condition. "make -j8" on a 16core
> > > machine can start making $(MKDOC) at the same time. How can move-if-change
> > > be 100% atomic?
> >
> > Well, 'mv -f' within a mount point is atomic, that's how.
>
> Ahh, move-if-change is broken: it doesn't ignore mv -f failure when the
> target is equal. Let's fix move-if-change.
Does this alternative (untested) patch fix the race?
Thanks,
Ralf
ChangeLog:
2010-12-02 Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
PR binutils/12283
* move-if-change: Ignore failure of 'mv -f' if the destination
is equal to the source afterwards.
diff --git a/move-if-change b/move-if-change
index ff74a55..1d2dd09 100755
--- a/move-if-change
+++ b/move-if-change
@@ -4,6 +4,8 @@
usage="$0: usage: $0 SOURCE DEST"
+cmpprog=${CMPPROG-cmp}
+
case $# in
2) ;;
*) echo "$usage" >&2; exit 1;;
@@ -18,5 +20,8 @@ done
if test -r "$2" && cmp -s "$1" "$2"; then
rm -f "$1"
else
- mv -f "$1" "$2"
+ if mv -f "$1" "$2"; then :; else
+ # Ignore failure due to a concurrent move-if-change.
+ $cmpprog "$1" "$2" >/dev/null 2>&1
+ fi
fi
next prev parent reply other threads:[~2010-12-02 18:32 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-02 17:00 H.J. Lu
2010-12-02 18:08 ` Ralf Wildenhues
2010-12-02 18:16 ` H.J. Lu
2010-12-02 18:20 ` Ralf Wildenhues
2010-12-02 18:22 ` Ralf Wildenhues
2010-12-02 18:32 ` Ralf Wildenhues [this message]
2010-12-02 18:40 ` H.J. Lu
2010-12-02 19:01 ` Ralf Wildenhues
2010-12-19 14:37 ` Ralf Wildenhues
2010-12-19 18:23 ` H.J. Lu
2011-01-27 23:57 ` Steve Ellcey
2011-01-28 20:15 ` PATCH: import move-if-change from gnulib (was: PATCH: PR binutils/12283: bfd/doc doesn't support parallel build) Ralf Wildenhues
2011-01-28 21:12 ` Steve Ellcey
2011-02-12 15:48 ` Ralf Wildenhues
2011-01-28 23:32 ` PATCH: PR binutils/12283: bfd/doc doesn't support parallel build Steve Ellcey
2011-01-29 9:42 ` Ralf Wildenhues
2011-01-31 18:33 ` Steve Ellcey
2011-02-04 6:34 ` Ralf Wildenhues
2011-02-04 17:51 ` Andreas Schwab
2011-02-16 0:07 ` Steve Ellcey
2011-02-16 5:09 ` Ralf Wildenhues
2011-02-16 18:36 ` Andreas Schwab
2011-02-05 0:25 ` Steve Ellcey
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