Rik van Riel [Sat, 23 Mar 2013 02:32:55 +0000 (13:32 +1100)]
ipc,sem: fine grained locking for semtimedop
Introduce finer grained locking for semtimedop, to handle the common case
of a program wanting to manipulate one semaphore from an array with
multiple semaphores.
If the call is a semop manipulating just one semaphore in an array with
multiple semaphores, only take the lock for that semaphore itself.
If the call needs to manipulate multiple semaphores, or another caller is
in a transaction that manipulates multiple semaphores, the sem_array lock
is taken, as well as all the locks for the individual semaphores.
On a 24 CPU system, performance numbers with the semop-multi
test with N threads and N semaphores, look like this:
Rik van Riel [Sat, 23 Mar 2013 02:32:55 +0000 (13:32 +1100)]
ipc,sem: have only one list in struct sem_queue
Having only one list in struct sem_queue, and only queueing simple
semaphore operations on the list for the semaphore involved, allows us to
introduce finer grained locking for semtimedop.
Signed-off-by: Rik van Riel <riel@redhat.com> Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Chegu Vinod <chegu_vinod@hp.com> Cc: Emmanuel Benisty <benisty.e@gmail.com> Cc: Jason Low <jason.low2@hp.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michel Lespinasse <walken@google.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2) While on an Oracle swingbench DSS (data mining) workload the
improvements are not as exciting as with Rik's benchmark, we can see
some positive numbers. For an 8 socket machine the following are the
percentages of %sys time incurred in the ipc lock:
Davidlohr Bueso [Sat, 23 Mar 2013 02:32:54 +0000 (13:32 +1100)]
ipc: introduce lockless pre_down ipcctl
Various forms of ipc use ipcctl_pre_down() to retrieve an ipc object and
check permissions, mostly for IPC_RMID and IPC_SET commands.
Introduce ipcctl_pre_down_nolock(), a lockless version of this function.
The locking version is retained, yet modified to call the nolock version
without affecting its semantics, thus transparent to all ipc callers.
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Signed-off-by: Rik van Riel <riel@redhat.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Chegu Vinod <chegu_vinod@hp.com> Cc: Emmanuel Benisty <benisty.e@gmail.com> Cc: Jason Low <jason.low2@hp.com> Cc: Michel Lespinasse <walken@google.com> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Davidlohr Bueso [Sat, 23 Mar 2013 02:32:53 +0000 (13:32 +1100)]
ipc: introduce obtaining a lockless ipc object
Through ipc_lock() and therefore ipc_lock_check() we currently return the
locked ipc object. This is not necessary for all situations and can,
therefore, cause unnecessary ipc lock contention.
Introduce analogous ipc_obtain_object() and ipc_obtain_object_check()
functions that only lookup and return the ipc object.
Both these functions must be called within the RCU read critical section.
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Signed-off-by: Rik van Riel <riel@redhat.com> Reviewed-by: Chegu Vinod <chegu_vinod@hp.com> Acked-by: Michel Lespinasse <walken@google.com> Cc: Emmanuel Benisty <benisty.e@gmail.com> Cc: Jason Low <jason.low2@hp.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Davidlohr Bueso [Sat, 23 Mar 2013 02:32:53 +0000 (13:32 +1100)]
ipc: remove bogus lock comment for ipc_checkid
This series makes the sysv semaphore code more scalable, by reducing the
time the semaphore lock is held, and making the locking more scalable for
semaphore arrays with multiple semaphores.
The first four patches were written by Davidlohr Buesso, and reduce the
hold time of the semaphore lock.
The last three patches change the sysv semaphore code locking to be more
fine grained, providing a performance boost when multiple semaphores in a
semaphore array are being manipulated simultaneously.
On a 24 CPU system, performance numbers with the semop-multi
test with N threads and N semaphores, look like this:
Peter Hurley [Sat, 23 Mar 2013 02:32:52 +0000 (13:32 +1100)]
ipc: refactor msg list search into separate function
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Peter Hurley [Sat, 23 Mar 2013 02:32:52 +0000 (13:32 +1100)]
ipc: simplify msg list search
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Peter Hurley [Sat, 23 Mar 2013 02:32:52 +0000 (13:32 +1100)]
ipc: implement MSG_COPY as a new receive mode
Teach the helper routines about MSG_COPY so that msgtyp is preserved as
the message number to copy.
The security functions affected by this change were audited and no
additional changes are necessary.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Peter Hurley [Sat, 23 Mar 2013 02:32:51 +0000 (13:32 +1100)]
ipc: remove msg handling from queue scan
In preparation for refactoring the queue scan into a separate
function, relocate msg copying.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Peter Hurley [Sat, 23 Mar 2013 02:32:51 +0000 (13:32 +1100)]
ipc: set EFAULT as default error in load_msg()
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Peter Hurley [Sat, 23 Mar 2013 02:32:51 +0000 (13:32 +1100)]
ipc: tighten msg copy loops
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Peter Hurley [Sat, 23 Mar 2013 02:32:50 +0000 (13:32 +1100)]
ipc: clamp with min()
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Oleg Nesterov [Sat, 23 Mar 2013 02:32:49 +0000 (13:32 +1100)]
exec: do not abuse ->cred_guard_mutex in threadgroup_lock()
threadgroup_lock() takes signal->cred_guard_mutex to ensure that
thread_group_leader() is stable. This doesn't look nice, the scope of
this lock in do_execve() is huge.
And as Dave pointed out this can lead to deadlock, we have the
following dependencies:
Change de_thread() to take threadgroup_change_begin() around the
switch-the-leader code and change threadgroup_lock() to avoid
->cred_guard_mutex.
Note that de_thread() can't sleep with ->group_rwsem held, this can
obviously deadlock with the exiting leader if the writer is active, so it
does threadgroup_change_end() before schedule().
Reported-by: Dave Jones <davej@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Nathan Zimmer [Sat, 23 Mar 2013 02:32:48 +0000 (13:32 +1100)]
procfs: improve scaling in proc
I am currently tracking a hotlock reported by a customer on a large
system, 512 cores. I am currently running 3.8-rc7 but the issue looks
like it has been this way for a very long time. The offending lock is
proc_dir_entry->pde_unload_lock.
This patch converts the lock to use rcu. However the pde_openers list
still is controlled by a spin lock. I tested on a 4096 machine and the
lock doesn't seem hot at least according to perf.
This is a refresh of what was orignally suggested by Eric Dumazet some
time ago. I have also taken in some comments from Andrew and several
other people whose names escape me but I am quite grateful too.
Supporting numbers, lower is better, they are from the test I posted earlier.
cpuinfo baseline Rcu
tasks read-sec read-sec
1 0.0141 0.0141
2 0.0140 0.0142
4 0.0140 0.0141
8 0.0145 0.0140
16 0.0553 0.0168
32 0.1688 0.0549
64 0.5017 0.1690
128 1.7005 0.5038
256 5.2513 2.0804
512 8.0529 3.0162
Signed-off-by: Nathan Zimmer <nzimmer@sgi.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Oleg Nesterov [Sat, 23 Mar 2013 02:32:48 +0000 (13:32 +1100)]
coredump: change wait_for_dump_helpers() to use wait_event_interruptible()
wait_for_dump_helpers() calls wake_up/kill_fasync from inside the
wait_event-like loop. This is not needed and in fact this is not strictly
correct, we can/should do this only once after we change pipe->writers.
We could even check if it becomes zero.
Change this code to use use wait_event_interruptible(), this can also help
to make this wait freezable.
With this patch we check pipe->readers without pipe_lock(), this is fine.
Once we see pipe->readers == 1 we know that the handler decremented the
counter, this is all we need.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Mandeep Singh Baines <msb@chromium.org> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Oleg Nesterov [Sat, 23 Mar 2013 02:32:47 +0000 (13:32 +1100)]
coredump: introduce dump_interrupted()
By discussion with Mandeep.
Change dump_write(), dump_seek() and do_coredump() to check
signal_pending() and abort if it is true. dump_seek() does this only
before f_op->llseek(), otherwise it relies on dump_write().
We need this change to ensure that the coredump won't delay suspend, and
to ensure it reacts to SIGKILL "quickly enough", a core dump can take a
lot of time. In particular this can help oom-killer.
We add the new trivial helper, dump_interrupted() to add the comments and
to simplify the potential freezer changes. Perhaps it will have more
callers.
Ideally it should do try_to_freeze() but then we need the unpleasant
changes in dump_write() and wait_for_dump_helpers(). It is not trivial to
change dump_write() to restart if f_op->write() fails because of
freezing(). We need to handle the short writes, we need to clear
TIF_SIGPENDING (and we can't rely on recalc_sigpending() unless we change
it to check PF_DUMPCORE). And if the buggy f_op->write() sets
TIF_SIGPENDING we can not distinguish this case from the race with
freeze_task() + __thaw_task().
So we simply accept the fact that the freezer can truncate a core-dump but
at least you can reliably suspend. Hopefully we can tolerate this
unlikely case and the necessary complications doesn't worth a trouble.
But if we decide to make the coredumping freezable later we can do this on
top of this change.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Mandeep Singh Baines <msb@chromium.org> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Oleg Nesterov [Sat, 23 Mar 2013 02:32:47 +0000 (13:32 +1100)]
coredump: sanitize the setting of signal->group_exit_code
Now that the coredumping process can be SIGKILL'ed, the setting of
->group_exit_code in do_coredump() can race with complete_signal() and
SIGKILL or 0x80 can be "lost", or wait(status) can report status ==
SIGKILL | 0x80.
But the main problem is that it is not clear to me what should we do if
binfmt->core_dump() succeeds but SIGKILL was sent, that is why this patch
comes as a separate change.
This patch adds 0x80 if ->core_dump() succeeds and the process was not
killed. But perhaps we can (should?) re-set ->group_exit_code changed by
SIGKILL back to "siginfo->si_signo |= 0x80" in case when core_dumped == T.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Tested-by: Mandeep Singh Baines <msb@chromium.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Roland McGrath <roland@hack.frob.com> Cc: Tejun Heo <tj@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Oleg Nesterov [Sat, 23 Mar 2013 02:32:47 +0000 (13:32 +1100)]
coredump: ensure that SIGKILL always kills the dumping thread
prepare_signal() blesses SIGKILL sent to the dumping process but this
signal can be "lost" anyway. The problems is, complete_signal() sees
SIGNAL_GROUP_EXIT and skips the "kill them all" logic. And even if the
dumping process is single-threaded (so the target is always "correct"),
the group-wide SIGKILL is not recorded in task->pending and thus
__fatal_signal_pending() won't be true. A multi-threaded case has even
more problems.
And even ignoring all technical details, SIGNAL_GROUP_EXIT doesn't look
right to me. This coredumping process is not exiting yet, it can do a lot
of work dumping the core.
With this patch the dumping process doesn't have SIGNAL_GROUP_EXIT, we set
signal->group_exit_task instead. This makes signal_group_exit() true and
thus this should equally close the races with exit/exec/stop but allows to
kill the dumping thread reliably.
Notes:
- It is not clear what should we do with ->group_exit_code
if the dumper was killed, see the next change.
- we need more (hopefully straightforward) changes to ensure
that SIGKILL actually interrupts the coredump. Basically we
need to check __fatal_signal_pending() in dump_write() and
dump_seek().
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Tested-by: Mandeep Singh Baines <msb@chromium.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Roland McGrath <roland@hack.frob.com> Cc: Tejun Heo <tj@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Oleg Nesterov [Sat, 23 Mar 2013 02:32:47 +0000 (13:32 +1100)]
coredump: only SIGKILL should interrupt the coredumping task
There are 2 well known and ancient problems with coredump/signals, and a
lot of related bug reports:
- do_coredump() clears TIF_SIGPENDING but of course this can't help
if, say, SIGCHLD comes after that.
In this case the coredump can fail unexpectedly. See for example
wait_for_dump_helper()->signal_pending() check but there are other
reasons.
- At the same time, dumping a huge core on the slow media can take a
lot of time/resources and there is no way to kill the coredumping
task reliably. In particular this is not oom_kill-friendly.
This patch tries to fix the 1st problem, and makes the preparation for the
next changes.
We add the new SIGNAL_GROUP_COREDUMP flag set by zap_threads() to indicate
that this process dumps the core. prepare_signal() checks this flag and
nacks any signal except SIGKILL.
Note that this check tries to be conservative, in the long term we should
probably treat the SIGNAL_GROUP_EXIT case equally but this needs more
discussion. See marc.info/?l=linux-kernel&m=120508897917439
Notes:
- recalc_sigpending() doesn't check SIGNAL_GROUP_COREDUMP.
The patch assumes that dump_write/etc paths should never
call it, but we can change it as well.
- There is another source of TIF_SIGPENDING, freezer. This
will be addressed separately.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Tested-by: Mandeep Singh Baines <msb@chromium.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Neil Horman <nhorman@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Roland McGrath <roland@hack.frob.com> Cc: Tejun Heo <tj@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lucas De Marchi [Sat, 23 Mar 2013 02:32:46 +0000 (13:32 +1100)]
kmod: remove call_usermodehelper_fns()
This function suffers from not being able to determine if the cleanup is
called in case it returns -ENOMEM. Nobody is using it anymore, so let's
remove it.
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Tejun Heo <tj@kernel.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lucas De Marchi [Sat, 23 Mar 2013 02:32:46 +0000 (13:32 +1100)]
usermodehelper: split remaining calls to call_usermodehelper_fns()
These are the only users of call_usermodehelper_fns(). This function
suffers from not being able to determine if the cleanup is called. Even
if in this places the cleanup pointer is NULL, convert them to use the
separate call_usermodehelper_setup() + call_usermodehelper_exec()
functions so we can remove the _fns variant.
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Tejun Heo <tj@kernel.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lucas De Marchi [Sat, 23 Mar 2013 02:32:46 +0000 (13:32 +1100)]
coredump: remove trailling whitespace
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Tejun Heo <tj@kernel.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lucas De Marchi [Sat, 23 Mar 2013 02:32:46 +0000 (13:32 +1100)]
KEYS: split call to call_usermodehelper_fns()
Use call_usermodehelper_setup() + call_usermodehelper_exec() instead of
calling call_usermodehelper_fns(). In case there's an OOM in this last
function the cleanup function may not be called - in this case we would
miss a call to key_put().
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Acked-by: James Morris <james.l.morris@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Tejun Heo <tj@kernel.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lucas De Marchi [Sat, 23 Mar 2013 02:32:45 +0000 (13:32 +1100)]
kmod: split call to call_usermodehelper_fns()
Use call_usermodehelper_setup() + call_usermodehelper_exec() instead of
calling call_usermodehelper_fns(). In case the latter returns -ENOMEM the
cleanup function may had not been called - in this case we would not free
argv and module_name.
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Tejun Heo <tj@kernel.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: David Howells <dhowells@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Lucas De Marchi <lucas.demarchi@profusion.mobi> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lucas De Marchi [Sat, 23 Mar 2013 02:32:45 +0000 (13:32 +1100)]
usermodehelper: export call_usermodehelper_exec() and call_usermodehelper_setup()
call_usermodehelper_setup() + call_usermodehelper_exec() need to be called
instead of call_usermodehelper_fns() when the cleanup function needs to be
called even when an ENOMEM error occurs. In this case using
call_usermodehelper_fns() the user can't distinguish if the cleanup
function was called or not.
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Tejun Heo <tj@kernel.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrey Vagin [Sat, 23 Mar 2013 02:32:44 +0000 (13:32 +1100)]
selftest: add a test case for PTRACE_PEEKSIGINFO
* Dump signals from process-wide and per-thread queues with
different sizes of buffers.
* Check error paths for buffers with restricted permissions. A part of
buffer or a whole buffer is for read-only.
* Try to get nonexistent signal.
Signed-off-by: Andrew Vagin <avagin@openvz.org> Cc: Roland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: David Howells <dhowells@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pedro Alves <palves@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrey Vagin [Sat, 23 Mar 2013 02:32:44 +0000 (13:32 +1100)]
ptrace: add ability to retrieve signals without removing from a queue (v4)
This patch adds a new ptrace request PTRACE_PEEKSIGINFO.
This request is used to retrieve information about pending signals
starting with the specified sequence number. Siginfo_t structures are
copied from the child into the buffer starting at "data".
The argument "addr" is a pointer to struct ptrace_peeksiginfo_args.
struct ptrace_peeksiginfo_args {
u64 off; /* from which siginfo to start */
u32 flags;
s32 nr; /* how may siginfos to take */
};
"nr" has type "s32", because ptrace() returns "long", which has 32 bits on
i386 and a negative values is used for errors.
Currently here is only one flag PTRACE_PEEKSIGINFO_SHARED for dumping
signals from process-wide queue. If this flag is not set, signals are
read from a per-thread queue.
The request PTRACE_PEEKSIGINFO returns a number of dumped signals. If a
signal with the specified sequence number doesn't exist, ptrace returns
zero. The request returns an error, if no signal has been dumped.
Errors:
EINVAL - one or more specified flags are not supported or nr is negative
EFAULT - buf or addr is outside your accessible address space.
A result siginfo contains a kernel part of si_code which usually striped,
but it's required for queuing the same siginfo back during restore of
pending signals.
This functionality is required for checkpointing pending signals. Pedro
Alves suggested using it in "gdb" to peek at pending signals. gdb already
uses PTRACE_GETSIGINFO to get the siginfo for the signal which was already
dequeued. This functionality allows gdb to look at the pending signals
which were not reported yet.
The prototype of this code was developed by Oleg Nesterov.
Signed-off-by: Andrew Vagin <avagin@openvz.org> Cc: Roland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: David Howells <dhowells@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pedro Alves <palves@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Namjae Jeon [Sat, 23 Mar 2013 02:32:43 +0000 (13:32 +1100)]
fat (exportfs): rebuild directory-inode if fat_dget()
This patch enables rebuilding of directory inodes which are not present in
the cache.This is done by traversing the disk clusters to find the
directory entry of the parent directory and using its i_pos to build the
inode.
The traversal is done by fat_scan_logstart() which is similar to
fat_scan() but matches i_pos values instead of names.fat_scan_logstart()
needs an inode parameter to work, for which a dummy inode is created by
it's caller fat_rebuild_parent(). This dummy inode is destroyed after the
traversal completes.
All this is done only if the nostale_ro nfs mount option is specified.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com> Signed-off-by: Ravishankar N <ravi.n1@samsung.com> Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Namjae Jeon [Sat, 23 Mar 2013 02:32:43 +0000 (13:32 +1100)]
fat (exportfs): rebuild inode if ilookup() fails
If the cache lookups fail,use the i_pos value to find the directory entry
of the inode and rebuild the inode.Since this involves accessing the FAT
media, do this only if the nostale_ro nfs mount option is specified.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com> Signed-off-by: Ravishankar N <ravi.n1@samsung.com> Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Namjae Jeon [Sat, 23 Mar 2013 02:32:43 +0000 (13:32 +1100)]
fat: restructure export_operations
Define two nfs export_operation structures,one for 'stale_rw' mounts and
the other for 'nostale_ro'. The latter uses i_pos as a basis for encoding
and decoding file handles.
Also, assign i_pos to kstat->ino. The logic for rebuilding the inode is
added in the subsequent patches.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com> Signed-off-by: Ravishankar N <ravi.n1@samsung.com> Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Namjae Jeon [Sat, 23 Mar 2013 02:32:42 +0000 (13:32 +1100)]
fat: introduce 2 new values for the -o nfs mount option
This patchset eliminates the client side ESTALE errors when a FAT
partition exported over NFS has its dentries evicted from the cache. The
idea is to find the on-disk location_'i_pos' of the dirent of the inode
that has been evicted and use it to rebuild the inode.
This patch:
Provide two possible values 'stale_rw' and 'nostale_ro' for the -o nfs
mount option.The first one allows all file operations but does not reduce
ESTALE errors on memory constrained systems. The second one eliminates
ESTALE errors but mounts the filesystem as read-only. Not specifying a
value defaults to 'stale_rw'.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com> Signed-off-by: Ravishankar N <ravi.n1@samsung.com> Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com> Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
fs/hfsplus/bfind.c: In function 'hfs_find_1st_rec_by_cnid':
(1) include/uapi/linux/swab.h:60:2: warning: 'search_cnid' may be used uninitialized in this function [-Wmaybe-uninitialized]
(2) include/uapi/linux/swab.h:60:2: warning: 'cur_cnid' may be used uninitialized in this function [-Wmaybe-uninitialized]
Signed-off-by: Vyacheslav Dubeyko <slava@dubeyko.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jingoo Han [Sat, 23 Mar 2013 02:32:41 +0000 (13:32 +1100)]
drivers/rtc/rtc-88pm80x.c: add CONFIG_PM_SLEEP to suspend/resume functions
Add CONFIG_PM_SLEEP to suspend/resume functions to fix the following build
warning when CONFIG_PM_SLEEP is not selected. This is because sleep PM
callbacks defined by SIMPLE_DEV_PM_OPS are only used when the
CONFIG_PM_SLEEP is enabled.
drivers/rtc/rtc-88pm80x.c:238:12: warning: 'pm80x_rtc_suspend' defined but not used [-Wunused-function]
drivers/rtc/rtc-88pm80x.c:243:12: warning: 'pm80x_rtc_resume' defined but not used [-Wunused-function]
Signed-off-by: Jingoo Han <jg1.han@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jingoo Han [Sat, 23 Mar 2013 02:32:41 +0000 (13:32 +1100)]
drivers/rtc/rtc-ds1374.c: add CONFIG_PM_SLEEP to suspend/resume functions
Add CONFIG_PM_SLEEP to suspend/resume functions to fix the following build
warning when CONFIG_PM_SLEEP is not selected. This is because sleep PM
callbacks defined by SIMPLE_DEV_PM_OPS are only used when the
CONFIG_PM_SLEEP is enabled.
drivers/rtc/rtc-ds1374.c:413:12: warning: 'ds1374_suspend' defined but not used [-Wunused-function]
drivers/rtc/rtc-ds1374.c:422:12: warning: 'ds1374_resume' defined but not used [-Wunused-function]
Signed-off-by: Jingoo Han <jg1.han@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jingoo Han [Sat, 23 Mar 2013 02:32:39 +0000 (13:32 +1100)]
rtc: rtc-sh: switch to using SIMPLE_DEV_PM_OPS
Switch to using the SIMPLE_DEV_PM_OPS macro to declare the driver's
pm_ops. It reduces code size. Also, CONFIG_PM_SLEEP is added to prevent
build warning when CONFIG_PM_SLEEP is not selected.
Signed-off-by: Jingoo Han <jg1.han@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jingoo Han [Sat, 23 Mar 2013 02:32:28 +0000 (13:32 +1100)]
drivers/rtc/rtc-s3c.c: convert s3c_rtc to dev_pm_ops
Instead of using legacy suspend/resume methods, using newer dev_pm_ops
structure allows better control over power management. Also, 'wake_en'
variable is moved, because it is only used when CONFIG_PM_SLEEP is
enabled.
Signed-off-by: Jingoo Han <jg1.han@samsung.com> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: Rob Herring <rob.herring@calxeda.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Bertrand Achard [Sat, 23 Mar 2013 02:32:28 +0000 (13:32 +1100)]
drivers/rtc/rtc-ds1307.c: long block operations bugfix
The rtc-ds1307 driver does not properly handle block operations bigger
than 32 bytes in either of the two modes supported (SMbus native, or
emulated if not supported by the SMbus platform driver).
It also does not properly handle userland-supplied input (block operation
length) through sysfs and may suffer a type of buffer overrun.
The driver has been modified with proper input validation, buffer sizes,
and now splits block transfers bigger than 32 bytes into separate
transfers.
Explanation : Buffer size allocated is I2C_SMBUS_BLOCK_MAX which equals to
32 as per the SMbus spec. Reads and write may be up to 56 bytes (to the
NVRAM). This patch allocated a 255 byte buffer, the maximum allowable
(address is an u8). It's not only a buffer problem, SMbus only supports
up to 32 bytes transfer at once, so it's needed to split bigger transfers.
Patch successfully tested on 3.2.27; cleanly applies on 3.7-rc4.
[akpm@linux-foundation.org: rework code to avoid 80-column overflows] Signed-off-by: Bertrand Achard <ba@cykian.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Laxman Dewangan [Sat, 23 Mar 2013 02:32:27 +0000 (13:32 +1100)]
drivers/rtc/rtc-tegra.c: fix build warning
Fix the below build warning:
drivers/rtc/rtc-tegra.c: In function 'tegra_rtc_probe':
drivers/rtc/rtc-tegra.c:353:33: warning: passing argument 1 of 'devm_rtc_device_register' from incompatible pointer type [enabled by default]
include/linux/rtc.h:136:27: note: expected 'struct device *' but argument is of type 'const char *'
drivers/rtc/rtc-tegra.c:353:33: warning: passing argument 2 of 'devm_rtc_device_register' from incompatible pointer type [enabled by default]
include/linux/rtc.h:136:27: note: expected 'const char *' but argument is of type 'struct device *'
projects / karo-tx-linux.git / log