<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/include/uapi, branch linux-3.7.y</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>ALSA: usb: Fix Processing Unit Descriptor parsers</title>
<updated>2013-02-27T17:21:10+00:00</updated>
<author>
<name>Pawel Moll</name>
<email>mail@pawelmoll.com</email>
</author>
<published>2013-02-21T01:55:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d451fb49065183643cc048ab9ee905e5c312219e'/>
<id>d451fb49065183643cc048ab9ee905e5c312219e</id>
<content type='text'>
commit b531f81b0d70ffbe8d70500512483227cc532608 upstream.

Commit 99fc86450c439039d2ef88d06b222fd51a779176 "ALSA: usb-mixer:
parse descriptors with structs" introduced a set of useful parsers
for descriptors. Unfortunately the parses for the Processing Unit
Descriptor came with a very subtle bug...

Functions uac_processing_unit_iProcessing() and
uac_processing_unit_specific() were indexing the baSourceID array
forgetting the fields before the iProcessing and process-specific
descriptors.

The problem was observed with Sound Blaster Extigy mixer,
where nNrModes in Up/Down-mix Processing Unit Descriptor
was accessed at offset 10 of the descriptor (value 0)
instead of offset 15 (value 7). In result the resulting
control had interesting limit values:

Simple mixer control 'Channel Routing Mode Select',0
  Capabilities: volume volume-joined penum
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - -1
  Mono: -1 [100%]

Fixed by starting from the bmControls, which was calculated
correctly, instead of baSourceID.

Now the mentioned control is fine:

Simple mixer control 'Channel Routing Mode Select',0
  Capabilities: volume volume-joined penum
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - 6
  Mono: 0 [0%]

Signed-off-by: Pawel Moll &lt;mail@pawelmoll.com&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit b531f81b0d70ffbe8d70500512483227cc532608 upstream.

Commit 99fc86450c439039d2ef88d06b222fd51a779176 "ALSA: usb-mixer:
parse descriptors with structs" introduced a set of useful parsers
for descriptors. Unfortunately the parses for the Processing Unit
Descriptor came with a very subtle bug...

Functions uac_processing_unit_iProcessing() and
uac_processing_unit_specific() were indexing the baSourceID array
forgetting the fields before the iProcessing and process-specific
descriptors.

The problem was observed with Sound Blaster Extigy mixer,
where nNrModes in Up/Down-mix Processing Unit Descriptor
was accessed at offset 10 of the descriptor (value 0)
instead of offset 15 (value 7). In result the resulting
control had interesting limit values:

Simple mixer control 'Channel Routing Mode Select',0
  Capabilities: volume volume-joined penum
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - -1
  Mono: -1 [100%]

Fixed by starting from the bmControls, which was calculated
correctly, instead of baSourceID.

Now the mentioned control is fine:

Simple mixer control 'Channel Routing Mode Select',0
  Capabilities: volume volume-joined penum
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - 6
  Mono: 0 [0%]

Signed-off-by: Pawel Moll &lt;mail@pawelmoll.com&gt;
Signed-off-by: Takashi Iwai &lt;tiwai@suse.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>serial_core: Fix type definition for PORT_BRCM_TRUMANAGE.</title>
<updated>2013-02-27T17:21:07+00:00</updated>
<author>
<name>Michael Chan</name>
<email>mchan@broadcom.com</email>
</author>
<published>2013-01-30T01:54:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3f1aaeede7bdd955b530522fe15cb663ee4f24d8'/>
<id>3f1aaeede7bdd955b530522fe15cb663ee4f24d8</id>
<content type='text'>
commit 85f024401bf80746ae08b7fd5809a9b16accf0b1 upstream.

It was mistakenly defined to be 24 instead of the next higher number 25.

Reported-by: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Stephen Hurd &lt;shurd@broadcom.com&gt;
Signed-off-by: Michael Chan &lt;mchan@broadcom.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 85f024401bf80746ae08b7fd5809a9b16accf0b1 upstream.

It was mistakenly defined to be 24 instead of the next higher number 25.

Reported-by: Alexander Shishkin &lt;alexander.shishkin@linux.intel.com&gt;
Cc: Stephen Hurd &lt;shurd@broadcom.com&gt;
Signed-off-by: Michael Chan &lt;mchan@broadcom.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>usb: Using correct way to clear usb3.0 device's remote wakeup feature.</title>
<updated>2013-02-11T17:04:45+00:00</updated>
<author>
<name>Lan Tianyu</name>
<email>tianyu.lan@intel.com</email>
</author>
<published>2013-01-24T02:31:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=390077b4fc3a6b8977e4586453124aaf655c3680'/>
<id>390077b4fc3a6b8977e4586453124aaf655c3680</id>
<content type='text'>
commit 54a3ac0c9e5b7213daa358ce74d154352657353a upstream.

Usb3.0 device defines function remote wakeup which is only for interface
recipient rather than device recipient. This is different with usb2.0 device's
remote wakeup feature which is defined for device recipient. According usb3.0
spec 9.4.5, the function remote wakeup can be modified by the SetFeature()
requests using the FUNCTION_SUSPEND feature selector. This patch is to use
correct way to disable usb3.0 device's function remote wakeup after suspend
error and resuming.

This should be backported to kernels as old as 3.4, that contain the
commit 623bef9e03a60adc623b09673297ca7a1cdfb367 "USB/xhci: Enable remote
wakeup for USB3 devices."

Signed-off-by: Lan Tianyu &lt;tianyu.lan@intel.com&gt;
Signed-off-by: Sarah Sharp &lt;sarah.a.sharp@linux.intel.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 54a3ac0c9e5b7213daa358ce74d154352657353a upstream.

Usb3.0 device defines function remote wakeup which is only for interface
recipient rather than device recipient. This is different with usb2.0 device's
remote wakeup feature which is defined for device recipient. According usb3.0
spec 9.4.5, the function remote wakeup can be modified by the SetFeature()
requests using the FUNCTION_SUSPEND feature selector. This patch is to use
correct way to disable usb3.0 device's function remote wakeup after suspend
error and resuming.

This should be backported to kernels as old as 3.4, that contain the
commit 623bef9e03a60adc623b09673297ca7a1cdfb367 "USB/xhci: Enable remote
wakeup for USB3 devices."

Signed-off-by: Lan Tianyu &lt;tianyu.lan@intel.com&gt;
Signed-off-by: Sarah Sharp &lt;sarah.a.sharp@linux.intel.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>8250/16?50: Add support for Broadcom TruManage redirected serial port</title>
<updated>2013-01-21T19:44:46+00:00</updated>
<author>
<name>Stephen Hurd</name>
<email>shurd@broadcom.com</email>
</author>
<published>2013-01-17T22:14:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7e9dbb269971d77c38fca3b6c4c1a716bbc26b0e'/>
<id>7e9dbb269971d77c38fca3b6c4c1a716bbc26b0e</id>
<content type='text'>
commit ebebd49a8eab5e9aa1b1f8f1614ccc3c2120f886 upstream.

Add support for the UART device present in Broadcom TruManage capable
NetXtreme chips (ie: 5761m 5762, and 5725).

This implementation has a hidden transmit FIFO, so running in single-byte
interrupt mode results in too many interrupts.  The UART_CAP_HFIFO
capability was added to track this.  It continues to reload the THR as long
as the THRE and TSRE bits are set in the LSR up to a specified limit (1024
is used here).

Signed-off-by: Stephen Hurd &lt;shurd@broadcom.com&gt;
Signed-off-by: Michael Chan &lt;mchan@broadcom.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit ebebd49a8eab5e9aa1b1f8f1614ccc3c2120f886 upstream.

Add support for the UART device present in Broadcom TruManage capable
NetXtreme chips (ie: 5761m 5762, and 5725).

This implementation has a hidden transmit FIFO, so running in single-byte
interrupt mode results in too many interrupts.  The UART_CAP_HFIFO
capability was added to track this.  It continues to reload the THR as long
as the THRE and TSRE bits are set in the LSR up to a specified limit (1024
is used here).

Signed-off-by: Stephen Hurd &lt;shurd@broadcom.com&gt;
Signed-off-by: Michael Chan &lt;mchan@broadcom.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>audit: create explicit AUDIT_SECCOMP event type</title>
<updated>2013-01-17T16:46:22+00:00</updated>
<author>
<name>Kees Cook</name>
<email>keescook@chromium.org</email>
</author>
<published>2013-01-11T22:32:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=2edbcdd71ca6c7751171221a559efcc3694c3694'/>
<id>2edbcdd71ca6c7751171221a559efcc3694c3694</id>
<content type='text'>
commit 7b9205bd775afc4439ed86d617f9042ee9e76a71 upstream.

The seccomp path was using AUDIT_ANOM_ABEND from when seccomp mode 1
could only kill a process.  While we still want to make sure an audit
record is forced on a kill, this should use a separate record type since
seccomp mode 2 introduces other behaviors.

In the case of "handled" behaviors (process wasn't killed), only emit a
record if the process is under inspection.  This change also fixes
userspace examination of seccomp audit events, since it was considered
malformed due to missing fields of the AUDIT_ANOM_ABEND event type.

Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Eric Paris &lt;eparis@redhat.com&gt;
Cc: Jeff Layton &lt;jlayton@redhat.com&gt;
Cc: "Eric W. Biederman" &lt;ebiederm@xmission.com&gt;
Cc: Julien Tinnes &lt;jln@google.com&gt;
Acked-by: Will Drewry &lt;wad@chromium.org&gt;
Acked-by: Steve Grubb &lt;sgrubb@redhat.com&gt;
Cc: Andrea Arcangeli &lt;aarcange@redhat.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 7b9205bd775afc4439ed86d617f9042ee9e76a71 upstream.

The seccomp path was using AUDIT_ANOM_ABEND from when seccomp mode 1
could only kill a process.  While we still want to make sure an audit
record is forced on a kill, this should use a separate record type since
seccomp mode 2 introduces other behaviors.

In the case of "handled" behaviors (process wasn't killed), only emit a
record if the process is under inspection.  This change also fixes
userspace examination of seccomp audit events, since it was considered
malformed due to missing fields of the AUDIT_ANOM_ABEND event type.

Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Eric Paris &lt;eparis@redhat.com&gt;
Cc: Jeff Layton &lt;jlayton@redhat.com&gt;
Cc: "Eric W. Biederman" &lt;ebiederm@xmission.com&gt;
Cc: Julien Tinnes &lt;jln@google.com&gt;
Acked-by: Will Drewry &lt;wad@chromium.org&gt;
Acked-by: Steve Grubb &lt;sgrubb@redhat.com&gt;
Cc: Andrea Arcangeli &lt;aarcange@redhat.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2012-12-01T21:07:48+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2012-12-01T21:07:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=455e987c0c2eb2c9045dc854559474cf41509965'/>
<id>455e987c0c2eb2c9045dc854559474cf41509965</id>
<content type='text'>
Pull perf fixes from Ingo Molnar:
 "This is mostly about unbreaking architectures that took the UAPI
  changes in the v3.7 cycle, plus misc fixes."

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf kvm: Fix building perf kvm on non x86 arches
  perf kvm: Rename perf_kvm to perf_kvm_stat
  perf: Make perf build for x86 with UAPI disintegration applied
  perf powerpc: Use uapi/unistd.h to fix build error
  tools: Pass the target in descend
  tools: Honour the O= flag when tool build called from a higher Makefile
  tools: Define a Makefile function to do subdir processing
  x86: Export asm/{svm.h,vmx.h,perf_regs.h}
  perf tools: Fix strbuf_addf() when the buffer needs to grow
  perf header: Fix numa topology printing
  perf, powerpc: Fix hw breakpoints returning -ENOSPC
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull perf fixes from Ingo Molnar:
 "This is mostly about unbreaking architectures that took the UAPI
  changes in the v3.7 cycle, plus misc fixes."

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf kvm: Fix building perf kvm on non x86 arches
  perf kvm: Rename perf_kvm to perf_kvm_stat
  perf: Make perf build for x86 with UAPI disintegration applied
  perf powerpc: Use uapi/unistd.h to fix build error
  tools: Pass the target in descend
  tools: Honour the O= flag when tool build called from a higher Makefile
  tools: Define a Makefile function to do subdir processing
  x86: Export asm/{svm.h,vmx.h,perf_regs.h}
  perf tools: Fix strbuf_addf() when the buffer needs to grow
  perf header: Fix numa topology printing
  perf, powerpc: Fix hw breakpoints returning -ENOSPC
</pre>
</div>
</content>
</entry>
<entry>
<title>perf: Make perf build for x86 with UAPI disintegration applied</title>
<updated>2012-11-19T22:21:03+00:00</updated>
<author>
<name>David Howells</name>
<email>dhowells@redhat.com</email>
</author>
<published>2012-11-19T22:21:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d2709c7ce4c513ab7f4ca9a106a930621811f2d3'/>
<id>d2709c7ce4c513ab7f4ca9a106a930621811f2d3</id>
<content type='text'>
Make perf build for x86 once the UAPI disintegration patches for that arch
have been applied by adding the appropriate -I flags - in the right order -
and then converting some #includes that use ../.. notation to find main kernel
headerfiles to use &lt;asm/foo.h&gt; and &lt;linux/foo.h&gt; instead.

Note that -Iarch/foo/include/uapi is present _before_ -Iarch/foo/include.
This makes sure we get the userspace version of the pt_regs struct.  Ideally,
we wouldn't have the latter -I flag at all, but unfortunately we want
asm/svm.h and asm/vmx.h in builtin-kvm.c and these aren't part of the UAPI -
at least not for x86.  I wonder if the bits outside of the __KERNEL__ guards
*should* be transferred there.

I note also that perf seems to do its dependency handling manually by listing
all the header files it might want to use in LIB_H in the Makefile.  Can this
be changed to use -MD?

Note that to do make this work, we need to export and UAPI disintegrate
linux/hw_breakpoint.h, which I think should've been exported previously so that
perf can access the bits.  We have to do this in the same patch to maintain
bisectability.

Signed-off-by: David Howells &lt;dhowells@redhat.com&gt;</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Make perf build for x86 once the UAPI disintegration patches for that arch
have been applied by adding the appropriate -I flags - in the right order -
and then converting some #includes that use ../.. notation to find main kernel
headerfiles to use &lt;asm/foo.h&gt; and &lt;linux/foo.h&gt; instead.

Note that -Iarch/foo/include/uapi is present _before_ -Iarch/foo/include.
This makes sure we get the userspace version of the pt_regs struct.  Ideally,
we wouldn't have the latter -I flag at all, but unfortunately we want
asm/svm.h and asm/vmx.h in builtin-kvm.c and these aren't part of the UAPI -
at least not for x86.  I wonder if the bits outside of the __KERNEL__ guards
*should* be transferred there.

I note also that perf seems to do its dependency handling manually by listing
all the header files it might want to use in LIB_H in the Makefile.  Can this
be changed to use -MD?

Note that to do make this work, we need to export and UAPI disintegrate
linux/hw_breakpoint.h, which I think should've been exported previously so that
perf can access the bits.  We have to do this in the same patch to maintain
bisectability.

Signed-off-by: David Howells &lt;dhowells@redhat.com&gt;</pre>
</div>
</content>
</entry>
<entry>
<title>mm, oom: reintroduce /proc/pid/oom_adj</title>
<updated>2012-11-16T18:15:35+00:00</updated>
<author>
<name>David Rientjes</name>
<email>rientjes@google.com</email>
</author>
<published>2012-11-13T01:53:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fa0cbbf145aabbf29c6f28f8a11935c0b0fd86fc'/>
<id>fa0cbbf145aabbf29c6f28f8a11935c0b0fd86fc</id>
<content type='text'>
This is mostly a revert of 01dc52ebdf47 ("oom: remove deprecated oom_adj")
from Davidlohr Bueso.

It reintroduces /proc/pid/oom_adj for backwards compatibility with earlier
kernels.  It simply scales the value linearly when /proc/pid/oom_score_adj
is written.

The major difference is that its scheduled removal is no longer included
in Documentation/feature-removal-schedule.txt.  We do warn users with a
single printk, though, to suggest the more powerful and supported
/proc/pid/oom_score_adj interface.

Reported-by: Artem S. Tashkinov &lt;t.artem@lycos.com&gt;
Signed-off-by: David Rientjes &lt;rientjes@google.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This is mostly a revert of 01dc52ebdf47 ("oom: remove deprecated oom_adj")
from Davidlohr Bueso.

It reintroduces /proc/pid/oom_adj for backwards compatibility with earlier
kernels.  It simply scales the value linearly when /proc/pid/oom_score_adj
is written.

The major difference is that its scheduled removal is no longer included
in Documentation/feature-removal-schedule.txt.  We do warn users with a
single printk, though, to suggest the more powerful and supported
/proc/pid/oom_score_adj interface.

Reported-by: Artem S. Tashkinov &lt;t.artem@lycos.com&gt;
Signed-off-by: David Rientjes &lt;rientjes@google.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>revert "epoll: support for disabling items, and a self-test app"</title>
<updated>2012-11-09T05:41:46+00:00</updated>
<author>
<name>Andrew Morton</name>
<email>akpm@linux-foundation.org</email>
</author>
<published>2012-11-08T23:53:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a80a6b85b428e6ce12a8363bb1f08d44c50f3252'/>
<id>a80a6b85b428e6ce12a8363bb1f08d44c50f3252</id>
<content type='text'>
Revert commit 03a7beb55b9f ("epoll: support for disabling items, and a
self-test app") pending resolution of the issues identified by Michael
Kerrisk, copied below.

We'll revisit this for 3.8.

: I've taken a look at this patch as it currently stands in 3.7-rc1, and
: done a bit of testing. (By the way, the test program
: tools/testing/selftests/epoll/test_epoll.c does not compile...)
:
: There are one or two places where the behavior seems a little strange,
: so I have a question or two at the end of this mail. But other than
: that, I want to check my understanding so that the interface can be
: correctly documented.
:
: Just to go though my understanding, the problem is the following
: scenario in a multithreaded application:
:
: 1. Multiple threads are performing epoll_wait() operations,
:    and maintaining a user-space cache that contains information
:    corresponding to each file descriptor being monitored by
:    epoll_wait().
:
: 2. At some point, a thread wants to delete (EPOLL_CTL_DEL)
:    a file descriptor from the epoll interest list, and
:    delete the corresponding record from the user-space cache.
:
: 3. The problem with (2) is that some other thread may have
:    previously done an epoll_wait() that retrieved information
:    about the fd in question, and may be in the middle of using
:    information in the cache that relates to that fd. Thus,
:    there is a potential race.
:
: 4. The race can't solved purely in user space, because doing
:    so would require applying a mutex across the epoll_wait()
:    call, which would of course blow thread concurrency.
:
: Right?
:
: Your solution is the EPOLL_CTL_DISABLE operation. I want to
: confirm my understanding about how to use this flag, since
: the description that has accompanied the patches so far
: has been a bit sparse
:
: 0. In the scenario you're concerned about, deleting a file
:    descriptor means (safely) doing the following:
:    (a) Deleting the file descriptor from the epoll interest list
:        using EPOLL_CTL_DEL
:    (b) Deleting the corresponding record in the user-space cache
:
: 1. It's only meaningful to use this EPOLL_CTL_DISABLE in
:    conjunction with EPOLLONESHOT.
:
: 2. Using EPOLL_CTL_DISABLE without using EPOLLONESHOT in
:    conjunction is a logical error.
:
: 3. The correct way to code multithreaded applications using
:    EPOLL_CTL_DISABLE and EPOLLONESHOT is as follows:
:
:    a. All EPOLL_CTL_ADD and EPOLL_CTL_MOD operations should
:       should EPOLLONESHOT.
:
:    b. When a thread wants to delete a file descriptor, it
:       should do the following:
:
:       [1] Call epoll_ctl(EPOLL_CTL_DISABLE)
:       [2] If the return status from epoll_ctl(EPOLL_CTL_DISABLE)
:           was zero, then the file descriptor can be safely
:           deleted by the thread that made this call.
:       [3] If the epoll_ctl(EPOLL_CTL_DISABLE) fails with EBUSY,
:           then the descriptor is in use. In this case, the calling
:           thread should set a flag in the user-space cache to
:           indicate that the thread that is using the descriptor
:           should perform the deletion operation.
:
: Is all of the above correct?
:
: The implementation depends on checking on whether
: (events &amp; ~EP_PRIVATE_BITS) == 0
: This replies on the fact that EPOLL_CTL_AD and EPOLL_CTL_MOD always
: set EPOLLHUP and EPOLLERR in the 'events' mask, and EPOLLONESHOT
: causes those flags (as well as all others in ~EP_PRIVATE_BITS) to be
: cleared.
:
: A corollary to the previous paragraph is that using EPOLL_CTL_DISABLE
: is only useful in conjunction with EPOLLONESHOT. However, as things
: stand, one can use EPOLL_CTL_DISABLE on a file descriptor that does
: not have EPOLLONESHOT set in 'events' This results in the following
: (slightly surprising) behavior:
:
: (a) The first call to epoll_ctl(EPOLL_CTL_DISABLE) returns 0
:     (the indicator that the file descriptor can be safely deleted).
: (b) The next call to epoll_ctl(EPOLL_CTL_DISABLE) fails with EBUSY.
:
: This doesn't seem particularly useful, and in fact is probably an
: indication that the user made a logic error: they should only be using
: epoll_ctl(EPOLL_CTL_DISABLE) on a file descriptor for which
: EPOLLONESHOT was set in 'events'. If that is correct, then would it
: not make sense to return an error to user space for this case?

Cc: Michael Kerrisk &lt;mtk.manpages@gmail.com&gt;
Cc: "Paton J. Lewis" &lt;palewis@adobe.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Revert commit 03a7beb55b9f ("epoll: support for disabling items, and a
self-test app") pending resolution of the issues identified by Michael
Kerrisk, copied below.

We'll revisit this for 3.8.

: I've taken a look at this patch as it currently stands in 3.7-rc1, and
: done a bit of testing. (By the way, the test program
: tools/testing/selftests/epoll/test_epoll.c does not compile...)
:
: There are one or two places where the behavior seems a little strange,
: so I have a question or two at the end of this mail. But other than
: that, I want to check my understanding so that the interface can be
: correctly documented.
:
: Just to go though my understanding, the problem is the following
: scenario in a multithreaded application:
:
: 1. Multiple threads are performing epoll_wait() operations,
:    and maintaining a user-space cache that contains information
:    corresponding to each file descriptor being monitored by
:    epoll_wait().
:
: 2. At some point, a thread wants to delete (EPOLL_CTL_DEL)
:    a file descriptor from the epoll interest list, and
:    delete the corresponding record from the user-space cache.
:
: 3. The problem with (2) is that some other thread may have
:    previously done an epoll_wait() that retrieved information
:    about the fd in question, and may be in the middle of using
:    information in the cache that relates to that fd. Thus,
:    there is a potential race.
:
: 4. The race can't solved purely in user space, because doing
:    so would require applying a mutex across the epoll_wait()
:    call, which would of course blow thread concurrency.
:
: Right?
:
: Your solution is the EPOLL_CTL_DISABLE operation. I want to
: confirm my understanding about how to use this flag, since
: the description that has accompanied the patches so far
: has been a bit sparse
:
: 0. In the scenario you're concerned about, deleting a file
:    descriptor means (safely) doing the following:
:    (a) Deleting the file descriptor from the epoll interest list
:        using EPOLL_CTL_DEL
:    (b) Deleting the corresponding record in the user-space cache
:
: 1. It's only meaningful to use this EPOLL_CTL_DISABLE in
:    conjunction with EPOLLONESHOT.
:
: 2. Using EPOLL_CTL_DISABLE without using EPOLLONESHOT in
:    conjunction is a logical error.
:
: 3. The correct way to code multithreaded applications using
:    EPOLL_CTL_DISABLE and EPOLLONESHOT is as follows:
:
:    a. All EPOLL_CTL_ADD and EPOLL_CTL_MOD operations should
:       should EPOLLONESHOT.
:
:    b. When a thread wants to delete a file descriptor, it
:       should do the following:
:
:       [1] Call epoll_ctl(EPOLL_CTL_DISABLE)
:       [2] If the return status from epoll_ctl(EPOLL_CTL_DISABLE)
:           was zero, then the file descriptor can be safely
:           deleted by the thread that made this call.
:       [3] If the epoll_ctl(EPOLL_CTL_DISABLE) fails with EBUSY,
:           then the descriptor is in use. In this case, the calling
:           thread should set a flag in the user-space cache to
:           indicate that the thread that is using the descriptor
:           should perform the deletion operation.
:
: Is all of the above correct?
:
: The implementation depends on checking on whether
: (events &amp; ~EP_PRIVATE_BITS) == 0
: This replies on the fact that EPOLL_CTL_AD and EPOLL_CTL_MOD always
: set EPOLLHUP and EPOLLERR in the 'events' mask, and EPOLLONESHOT
: causes those flags (as well as all others in ~EP_PRIVATE_BITS) to be
: cleared.
:
: A corollary to the previous paragraph is that using EPOLL_CTL_DISABLE
: is only useful in conjunction with EPOLLONESHOT. However, as things
: stand, one can use EPOLL_CTL_DISABLE on a file descriptor that does
: not have EPOLLONESHOT set in 'events' This results in the following
: (slightly surprising) behavior:
:
: (a) The first call to epoll_ctl(EPOLL_CTL_DISABLE) returns 0
:     (the indicator that the file descriptor can be safely deleted).
: (b) The next call to epoll_ctl(EPOLL_CTL_DISABLE) fails with EBUSY.
:
: This doesn't seem particularly useful, and in fact is probably an
: indication that the user made a logic error: they should only be using
: epoll_ctl(EPOLL_CTL_DISABLE) on a file descriptor for which
: EPOLLONESHOT was set in 'events'. If that is correct, then would it
: not make sense to return an error to user space for this case?

Cc: Michael Kerrisk &lt;mtk.manpages@gmail.com&gt;
Cc: "Paton J. Lewis" &lt;palewis@adobe.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'md-3.7-fixes' of git://neil.brown.name/md</title>
<updated>2012-10-31T02:48:48+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2012-10-31T02:48:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=2df4f26167ab6adc7d2648f57f433ff461965fc8'/>
<id>2df4f26167ab6adc7d2648f57f433ff461965fc8</id>
<content type='text'>
Pull md fixes from NeilBrown:
 "Some fixes for md in 3.7
   - one recently introduced crash for dm-raid10 with discard
   - one bug in new functionality that has been around for a few
     releases.
   - minor bug in md's 'faulty' personality

  and UAPI disintegration for md."

* tag 'md-3.7-fixes' of git://neil.brown.name/md:
  MD RAID10: Fix oops when creating RAID10 arrays via dm-raid.c
  md/raid1: Fix assembling of arrays containing Replacements.
  md faulty: use disk_stack_limits()
  UAPI: (Scripted) Disintegrate include/linux/raid
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull md fixes from NeilBrown:
 "Some fixes for md in 3.7
   - one recently introduced crash for dm-raid10 with discard
   - one bug in new functionality that has been around for a few
     releases.
   - minor bug in md's 'faulty' personality

  and UAPI disintegration for md."

* tag 'md-3.7-fixes' of git://neil.brown.name/md:
  MD RAID10: Fix oops when creating RAID10 arrays via dm-raid.c
  md/raid1: Fix assembling of arrays containing Replacements.
  md faulty: use disk_stack_limits()
  UAPI: (Scripted) Disintegrate include/linux/raid
</pre>
</div>
</content>
</entry>
</feed>
