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This removes the implementation of the big kernel lock,
at last. A lot of people have worked on this in the
past, I so the credit for this patch should be with
everyone who participated in the hunt.
The names on the Cc list are the people that were the
most active in this, according to the recorded git
history, in alphabetical order.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Alan Cox <alan@linux.intel.com>
Cc: Alessio Igor Bogani <abogani@texware.it>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Hendry <andrew.hendry@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Jan Blunck <jblunck@infradead.org>
Cc: John Kacur <jkacur@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: Paul Menage <menage@google.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
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Arnd Bergmann did an automated scripting run to find left-over instances
of <linux/smp_lock.h>, and had made it trigger it on the normal BKL use
of lock_kernel and unlock_lernel (and apparently release_kernel_lock and
reacquire_kernel_lock too, used by the scheduler).
That resulted in commit 451a3c24b013 ("BKL: remove extraneous #include
<smp_lock.h>").
However, hardirq.h was the only remaining user of the old
'kernel_locked()' interface, and Arnd's script hadn't checked for that.
So depending on your configuration and what header files had been
included, you would get errors like "implicit declaration of function
'kernel_locked'" during the build.
The right fix is not to just re-instate the smp_lock.h include - it is
to just remove 'kernel_locked()' entirely, since the only use was this
one special low-level detail. Just make hardirq.h do it directly.
In fact this simplifies and clarifies the code, because some trivial
analysis makes it clear that hardirq.h only ever used _one_ of the two
definitions of kernel_locked(), so we can remove the other one entirely.
Reported-by: Zimny Lech <napohybelskurwysynom2010@gmail.com>
Reported-and-acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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With all the patches we have queued in the BKL removal tree, only a
few dozen modules are left that actually rely on the BKL, and even
there are lots of low-hanging fruit. We need to decide what to do
about them, this patch illustrates one of the options:
Every user of the BKL is marked as 'depends on BKL' in Kconfig,
and the CONFIG_BKL becomes a user-visible option. If it gets
disabled, no BKL using module can be built any more and the BKL
code itself is compiled out.
The one exception is file locking, which is practically always
enabled and does a 'select BKL' instead. This effectively forces
CONFIG_BKL to be enabled until we have solved the fs/lockd
mess and can apply the patch that removes the BKL from fs/locks.c.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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Currently we are calling the bkl tracepoint callbacks just before the
bkl lock/unlock operations, ie the tracepoint call is not inside a
lock_kernel() function but inside a lock_kernel() macro. Hence the
bkl trace event header must be included from smp_lock.h. This raises
some nasty circular header dependencies:
linux/smp_lock.h -> trace/events/bkl.h -> trace/define_trace.h
-> trace/ftrace.h -> linux/ftrace_event.h -> linux/hardirq.h
-> linux/smp_lock.h
This results in incomplete event declarations, spurious event
definitions and other kind of funny behaviours.
This is hardly fixable without ugly workarounds. So instead, we push
the file name, line number and function name as lock_kernel()
parameters, so that we only deal with the trace event header from
lib/kernel_lock.c
This adds two parameters to lock_kernel() and unlock_kernel() but
it should be fine wrt to performances because this pair dos not seem
to be called in fast paths.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Li Zefan <lizf@cn.fujitsu.com>
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Add two events lock_kernel and unlock_kernel() to trace the bkl uses.
This opens the door for userspace tools to perform statistics about
the callsites that use it, dependencies with other locks (by pairing
the trace with lock events), use with recursivity and so on...
The {__reacquire,release}_kernel_lock() events are not traced because
these are called from schedule, thus the sched events are sufficient
to trace them.
Example of a trace:
hald-addon-stor-4152 [000] 165.875501: unlock_kernel: depth: 0, fs/block_dev.c:1358 __blkdev_put()
hald-addon-stor-4152 [000] 167.832974: lock_kernel: depth: 0, fs/block_dev.c:1167 __blkdev_get()
How to get the callsites that acquire it recursively:
cd /debug/tracing/events/bkl
echo "lock_depth > 0" > filter
firefox-4951 [001] 206.276967: unlock_kernel: depth: 1, fs/reiserfs/super.c:575 reiserfs_dirty_inode()
You can also filter by file and/or line.
v2: Use of FILTER_PTR_STRING attribute for files and lines fields to
make them traceable.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
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A number of driver functions are so obviously trivial that they do not need
the big kernel lock - at least not overtly. It turns out that the
acquisition of the BKL in driver open() functions can perform a sort of
poor-hacker's serialization function, delaying the open operation until the
driver is certain to have completed its initialization. Add a simple
cycle_kernel_lock() function for these cases to make it clear that there is
no need to *hold* the BKL, just to be sure that we can acquire it.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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remove the !PREEMPT_BKL code.
this removes 160 lines of legacy code.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Remove the obviously unnecessary includes of <linux/spinlock.h> under the
include/linux/ directory, and fix the couple errors that are introduced as
a result of that.
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: David Woodhouse <dwmw2@infradead.org>
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a) in smp_lock.h #include of sched.h and spinlock.h moved under #ifdef
CONFIG_LOCK_KERNEL.
b) interrupt.h now explicitly pulls sched.h (not via smp_lock.h from
hardirq.h as it used to)
c) in three more places we need changes to compensate for (a) - one place
in arch/sparc needs string.h now, hardirq.h needs forward declaration of
task_struct and preempt.h needs direct include of thread_info.h.
d) thread_info-related helpers in sched.h and thread_info.h put under
ifndef __HAVE_THREAD_FUNCTIONS. Obviously safe.
Signed-off-by: Al Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
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