1d09c1500f
futex.2: Fixes after feedback from Thomas Gleixner
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Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
ca4e5b2b99
futex.2: Minor wording fixes
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
601399f31f
futex.2: Improvements after comments from Darren Hart
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Reported-by: Darren Hart <dvhart@infradead.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
adc89a976e
futex.2: ffix
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
41b6c6a080
futex.2: srcfix: FIXME
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
c3875d1d3a
futex.2: Fixes after review comments from Thomas Gleixner
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Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
30239c10a8
futex.2: Various fixes after comments from Thomas Gleixner
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Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
aab5ca4b64
futex.2: wfix
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
f0a9e8f4ce
futex.2: tfix
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
39e9b2e1e4
futex.2: wfix
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
9cee832c40
futex.2: wfix
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
ac89487996
futex.2: Fixes after review comments from Thomas Gleixner
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Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
dcb410c3c8
futex.2: tfix
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:49 +01:00
627b50ce7c
futex.2: Elaborate on why "requeue" operations can be preferable to FUTEX_WAKE
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Cowritten-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
8297383e9e
futex.2: Clean-ups and FIXME removeal after feedback from Thomas Gleixner
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Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
27dd3a6e79
futex.2: Remove warning that FUTEX_REQUEUE is broken
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Darren Hart pointed me to the comments from Rich Felker
that there are valid use cases for FUTEX_REQUEUE.
From: Rich Felker <dalias@libc.org>
Date: Wed, 29 Oct 2014 22:43:17 -0400
To: Darren Hart <dvhart@infradead.org>
Cc: GLIBC Devel <libc-alpha@sourceware.org>, ...
Subject: Re: Add futex wrapper to glibc?
On Wed, Oct 29, 2014 at 06:59:15PM -0700, Darren Hart wrote:
[...]
> I wonder though... can we not wrap FUTEX_REQUEUE? It's fundamentally
> broken. FUTEX_CMP_REQUEUE should *always* be used instead. The glibc
> wrapper is one way to encourage developers to do the right thing
> (don't expose the bad op in the header).
You're mistaken here. There are plenty of valid ways to use
FUTEX_REQUEUE - for example if the calling thread is requeuing the
target(s) to a lock that the calling thread owns. Just because it
doesn't meet the needs of the way glibc was using it internally
doesn't mean it's useless for other applications.
Reported-by: Darren Hart <dvhart@infradead.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
da56650ae4
futex.2: srcfix
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
fd1056148b
futex.2: Minor wording fixes
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
55f9e85ead
futex.2: Minor wording fixes
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
b0f35fbb09
futex.2: tfix
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
c0dc758efd
futex.2: Rewrap some source lines (no content changes)
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
9d32a39b82
futex.2: Minor wording fixes
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
d45f244c6d
futex.2: Minor wording fixes
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
7e8dcabcb1
futex.2: Reword paragraph describing futex word
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Reported-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
02f7b623c9
futex.2: NOTES: futexes are also used to implement read-write locks and barriers
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
e0074751c9
futex.2: SEE ALSO: add pthread_mutexattr_getprotocol(3)
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Reported-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
36a90a75ce
futex.2: wfix
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Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
d6bb5a38db
futex.2: Tidy up some FIXMEs
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
cf44281c66
futex.2: Point out that futexes are used to implement higher-level abstractions
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Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Torvald Riegel <triegel@redhat.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
78bbcd9faf
futex.2: Remove an obsolete FIXME
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Reviewed-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
cabee29d5e
futex.2: tfix
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Reported-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
e61abc2018
futex.2: tfix
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Reported-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
a5c5a06aba
futex.2: Clarify return value details
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Reporte-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
943ccc5228
futex.2: Remove detail about kernel internals
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As commented on by Davidlohr Bueso:
This to me reads a bit too much into the kernel (fastpath,
refcnt, vmas). Why not just mention that it avoids overhead
in the kernel or something? I don't recall any manpage
mentioning such details, but I could be wrong.
Reported-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
10022b8e63
futex.2: Casting utime to uint32_t
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The kernel uses the following cast:
if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)
val2 = (u32) (unsigned long) utime;
This ensures that always the least significant four bytes of the
pointer are used, both on ILP32 and LP64 systems.
On a big endian system a simple cast from 64 bit pointer to 32 bit
integer would return the most significant four bytes.
We have to make the reader of the man-page aware of the usage
of the least significant bytes.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
c6dc40a2c9
futex.2: Use known types
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Type u32 is not exposed to the user. Instead, refer to uint32_t,
which is defined in ISO/IEC 9899:1999.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
d725ab772e
futex.2: tfix
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Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
78e856927e
futex.2: wfix
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
0c3ec26b07
futex.2: Minor wording fixes
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
8e754e12c5
futex.2: explanation of blocking
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Use shorter sentences.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:48 +01:00
b80daba225
futex.2: explanation of blocking behavior
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Shorten overlong sentence.
Highlight futex().
Tfix.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:47 +01:00
344df36631
futex.2: clarify address mapping
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Using the word "physical" address should make the text easier to
make.
Avoid negations like "may not be equal".
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:47 +01:00
594536fb2c
futex.2: tfix
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Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:47 +01:00
4c8cb0ffe6
futex.2: Rewrap some long source lines
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:47 +01:00
83e80dda44
futex.2: ffix
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:47 +01:00
63ad44cb92
futex.2: simplify example
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Do not duplicate coding.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:47 +01:00
92a4669004
futex.2: futex.2: Fix error check in EXAMPLE: fork() fails with -1
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Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:47 +01:00
357646628c
futex.2: tfix
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:47 +01:00
077981d467
futex.2: Wrap sentences at line boundaries
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Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:47 +01:00
74f58a643b
futex.2: Explicitly mark FIXMEs added by Torvald Riegel
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Mainly so I can keep track of who said what should be fixed/checked
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2015-12-15 14:39:47 +01:00
Michael Kerrisk