- 02 2月, 2006 1 次提交
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由 Alexey Dobriyan 提交于
On alpha-jensen: CC drivers/base/platform.o In file included from include/linux/dma-mapping.h:24, from drivers/base/platform.c:16: include/asm/dma-mapping.h:36: warning: "struct scatterlist" declared inside parameter list include/asm/dma-mapping.h:36: warning: its scope is only this definition or declaration, which is probably not what you want Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 13 1月, 2006 5 次提交
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由 Al Viro 提交于
{get,put}_thread_info() were introduced in 2.5.4 and never had been called by anything in the tree. Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 akpm@osdl.org 提交于
) From: Al Viro <viro@ftp.linux.org.uk> rename alpha_task_regs() to task_pt_regs(), switch open-coded instances to use of the helper. Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Al Viro 提交于
use task_stack_page() for accesses to stack page of task in alpha-specific parts of tree Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Al Viro 提交于
use task_thread_info() for accesses to thread_info of task in arch/alpha and include/asm-alpha Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Ingo Molnar 提交于
Add per-arch sched_cacheflush() which is a write-back cacheflush used by the migration-cost calibration code at bootup time. Signed-off-by: NIngo Molnar <mingo@elte.hu> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 10 1月, 2006 2 次提交
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由 Arjan van de Ven 提交于
add the per-arch mutex.h files for the remaining architectures. We default to asm-generic/mutex-dec.h, because that performs quite well on most arches. Arches that do not have atomic decrement/increment instructions should switch to mutex-xchg.h instead. Arches can also provide their own implementation for the mutex fastpath primitives. Signed-off-by: NArjan van de Ven <arjan@infradead.org> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Ingo Molnar 提交于
add atomic_xchg() to all the architectures. Needed by the new mutex code. Signed-off-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NArjan van de Ven <arjan@infradead.org>
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- 09 1月, 2006 3 次提交
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由 Andrew Morton 提交于
Remove various things which were checking for gcc-1.x and gcc-2.x compilers. From: Adrian Bunk <bunk@stusta.de> Some documentation updates and removes some code paths for gcc < 3.2. Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: NAdrian Bunk <bunk@stusta.de> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Jeff Dike 提交于
Most of the architectures have the same asm/futex.h. This consolidates them into asm-generic, with the arches including it from their own asm/futex.h. In the case of UML, this reverts the old broken futex.h and goes back to using the same one as almost everyone else. Signed-off-by: NJeff Dike <jdike@addtoit.com> Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Ravikiran G Thirumalai 提交于
Kill L1_CACHE_SHIFT from all arches. Since L1_CACHE_SHIFT_MAX is not used anymore with the introduction of INTERNODE_CACHE, kill L1_CACHE_SHIFT_MAX. Signed-off-by: NRavikiran Thirumalai <kiran@scalex86.org> Signed-off-by: NShai Fultheim <shai@scalex86.org> Signed-off-by: NAndi Kleen <ak@suse.de> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 07 1月, 2006 4 次提交
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由 Ivan Kokshaysky 提交于
Kconfig tweaks and tons of deletions. Signed-off-by: NIvan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Christoph Hellwig <hch@lst.de> Cc: Richard Henderson <rth@twiddle.net> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Christoph Lameter 提交于
Several counters already have the need to use 64 atomic variables on 64 bit platforms (see mm_counter_t in sched.h). We have to do ugly ifdefs to fall back to 32 bit atomic on 32 bit platforms. The VM statistics patch that I am working on will also make more extensive use of atomic64. This patch introduces a new type atomic_long_t by providing definitions in asm-generic/atomic.h that works similar to the c "long" type. Its 32 bits on 32 bit platforms and 64 bits on 64 bit platforms. Also cleans up the determination of the mm_counter_t in sched.h. Signed-off-by: NChristoph Lameter <clameter@sgi.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Badari Pulavarty 提交于
Here is the patch to implement madvise(MADV_REMOVE) - which frees up a given range of pages & its associated backing store. Current implementation supports only shmfs/tmpfs and other filesystems return -ENOSYS. "Some app allocates large tmpfs files, then when some task quits and some client disconnect, some memory can be released. However the only way to release tmpfs-swap is to MADV_REMOVE". - Andrea Arcangeli Databases want to use this feature to drop a section of their bufferpool (shared memory segments) - without writing back to disk/swap space. This feature is also useful for supporting hot-plug memory on UML. Concerns raised by Andrew Morton: - "We have no plan for holepunching! If we _do_ have such a plan (or might in the future) then what would the API look like? I think sys_holepunch(fd, start, len), so we should start out with that." - Using madvise is very weird, because people will ask "why do I need to mmap my file before I can stick a hole in it?" - None of the other madvise operations call into the filesystem in this manner. A broad question is: is this capability an MM operation or a filesytem operation? truncate, for example, is a filesystem operation which sometimes has MM side-effects. madvise is an mm operation and with this patch, it gains FS side-effects, only they're really, really significant ones." Comments: - Andrea suggested the fs operation too but then it's more efficient to have it as a mm operation with fs side effects, because they don't immediatly know fd and physical offset of the range. It's possible to fixup in userland and to use the fs operation but it's more expensive, the vmas are already in the kernel and we can use them. Short term plan & Future Direction: - We seem to need this interface only for shmfs/tmpfs files in the short term. We have to add hooks into the filesystem for correctness and completeness. This is what this patch does. - In the future, plan is to support both fs and mmap apis also. This also involves (other) filesystem specific functions to be implemented. - Current patch doesn't support VM_NONLINEAR - which can be addressed in the future. Signed-off-by: NBadari Pulavarty <pbadari@us.ibm.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Andrea Arcangeli <andrea@suse.de> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Cc: Ulrich Drepper <drepper@redhat.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Andrew Morton 提交于
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Richard Henderson <rth@twiddle.net> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 04 1月, 2006 1 次提交
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由 Stephen Hemminger 提交于
Signed-off-by: NStephen Hemminger <shemminger@osdl.org> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 24 11月, 2005 1 次提交
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由 Hugh Dickins 提交于
alpha, sparc64, x86_64 are each missing some primitives from their atomic64 support: fill in the gaps I've noticed by extrapolating asm, follow the groupings in each file. But powerpc and parisc still lack atomic64. Signed-off-by: NHugh Dickins <hugh@veritas.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: "David S. Miller" <davem@davemloft.net> Cc: Andi Kleen <ak@muc.de> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 14 11月, 2005 2 次提交
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由 Nick Piggin 提交于
Introduce an atomic_inc_not_zero operation. Make this a special case of atomic_add_unless because lockless pagecache actually wants atomic_inc_not_negativeone due to its offset refcount. Signed-off-by: NNick Piggin <npiggin@suse.de> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Nick Piggin 提交于
Introduce an atomic_cmpxchg operation. Signed-off-by: NNick Piggin <npiggin@suse.de> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 10 11月, 2005 1 次提交
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由 Bjorn Helgaas 提交于
CONFIG_IDE_MAX_HWIFS is a generic thing, no need to have it duplicated by every arch that uses it. Signed-off-by: NBjorn Helgaas <bjorn.helgaas@hp.com> Signed-off-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
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- 07 11月, 2005 2 次提交
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由 Christoph Hellwig 提交于
The sys_ptrace boilerplate code (everything outside the big switch statement for the arch-specific requests) is shared by most architectures. This patch moves it to kernel/ptrace.c and leaves the arch-specific code as arch_ptrace. Some architectures have a too different ptrace so we have to exclude them. They continue to keep their implementations. For sh64 I had to add a sh64_ptrace wrapper because it does some initialization on the first call. For um I removed an ifdefed SUBARCH_PTRACE_SPECIAL block, but SUBARCH_PTRACE_SPECIAL isn't defined anywhere in the tree. Signed-off-by: NChristoph Hellwig <hch@lst.de> Acked-by: NPaul Mackerras <paulus@samba.org> Acked-by: NRalf Baechle <ralf@linux-mips.org> Acked-By: NDavid Howells <dhowells@redhat.com> Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk> Acked-by: NPaul Mundt <lethal@linux-sh.org> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Tim Schmielau 提交于
Fix more include file problems that surfaced since I submitted the previous fix-missing-includes.patch. This should now allow not to include sched.h from module.h, which is done by a followup patch. Signed-off-by: NTim Schmielau <tim@physik3.uni-rostock.de> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 31 10月, 2005 1 次提交
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由 Arthur Othieno 提交于
__MUTEX_INITIALIZER() has no users, and equates to the more commonly used DECLARE_MUTEX(), thus making it pretty much redundant. Remove it for good. Signed-off-by: NArthur Othieno <a.othieno@bluewin.ch> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 30 10月, 2005 2 次提交
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由 Rik Van Riel 提交于
Add sem_is_read/write_locked functions to the read/write semaphores, along the same lines of the *_is_locked spinlock functions. The swap token tuning patch uses sem_is_read_locked; sem_is_write_locked is added for completeness. Signed-off-by: NRik van Riel <riel@redhat.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Ivan Kokshaysky 提交于
barrier.h uses barrier() in non-SMP case. And doesn't include compiler.h. Cc: Al Viro <viro@ftp.linux.org.uk> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 28 10月, 2005 1 次提交
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 26 10月, 2005 1 次提交
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由 Andrew Morton 提交于
My alpha build is exploding because asm/atomic.h now needs smb_mb(), which is over in the (not included) system.h. I fear what will happen if I include system.h into atomic.h, so let's put the barriers into their own header file. Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 23 10月, 2005 1 次提交
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由 Ivan Kokshaysky 提交于
As stated in Documentation/atomic_ops.txt, atomic functions returning values must have the memory barriers both before and after the operation. Thanks to DaveM for pointing that out. Signed-off-by: NIvan Kokshaysky <ink@jurassic.park.msu.ru> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 23 9月, 2005 1 次提交
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由 Ivan Kokshaysky 提交于
It is essential that index_of() be inlined. But alpha undoes the gcc inlining hackery and index_of() ends up out-of-line. So fiddle with things to make that function inline again. Cc: Richard Henderson <rth@twiddle.net> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 22 9月, 2005 1 次提交
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As recently done by Russell King for ARM, commit 4732efbe introduces a generic asm/futex.h copied along most arches, which includes a "-ENOSYS support" to be changed if needed. However, it includes an unused var (taken from the "real" version) which GCC warns about. Remove it from all arches having that file version (i.e. same GIT id). $ git-diff-tree -r HEAD and $ git-ls-tree -r HEAD include/|grep 9feff4ce1424bc390608326240be369eb13aa648 may be more interesting than looking at the patch itself, to make sure I've just copied the arm header to all other archs having the original dummy version of this file. Cc: Jakub Jelinek <jakub@redhat.com> Signed-off-by: NPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 13 9月, 2005 1 次提交
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由 Randy Dunlap 提交于
As written in Documentation/feature-removal-schedule.txt, remove the io_remap_page_range() kernel API. Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 11 9月, 2005 1 次提交
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由 Ingo Molnar 提交于
This patch (written by me and also containing many suggestions of Arjan van de Ven) does a major cleanup of the spinlock code. It does the following things: - consolidates and enhances the spinlock/rwlock debugging code - simplifies the asm/spinlock.h files - encapsulates the raw spinlock type and moves generic spinlock features (such as ->break_lock) into the generic code. - cleans up the spinlock code hierarchy to get rid of the spaghetti. Most notably there's now only a single variant of the debugging code, located in lib/spinlock_debug.c. (previously we had one SMP debugging variant per architecture, plus a separate generic one for UP builds) Also, i've enhanced the rwlock debugging facility, it will now track write-owners. There is new spinlock-owner/CPU-tracking on SMP builds too. All locks have lockup detection now, which will work for both soft and hard spin/rwlock lockups. The arch-level include files now only contain the minimally necessary subset of the spinlock code - all the rest that can be generalized now lives in the generic headers: include/asm-i386/spinlock_types.h | 16 include/asm-x86_64/spinlock_types.h | 16 I have also split up the various spinlock variants into separate files, making it easier to see which does what. The new layout is: SMP | UP ----------------------------|----------------------------------- asm/spinlock_types_smp.h | linux/spinlock_types_up.h linux/spinlock_types.h | linux/spinlock_types.h asm/spinlock_smp.h | linux/spinlock_up.h linux/spinlock_api_smp.h | linux/spinlock_api_up.h linux/spinlock.h | linux/spinlock.h /* * here's the role of the various spinlock/rwlock related include files: * * on SMP builds: * * asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the * initializers * * linux/spinlock_types.h: * defines the generic type and initializers * * asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel * implementations, mostly inline assembly code * * (also included on UP-debug builds:) * * linux/spinlock_api_smp.h: * contains the prototypes for the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. * * on UP builds: * * linux/spinlock_type_up.h: * contains the generic, simplified UP spinlock type. * (which is an empty structure on non-debug builds) * * linux/spinlock_types.h: * defines the generic type and initializers * * linux/spinlock_up.h: * contains the __raw_spin_*()/etc. version of UP * builds. (which are NOPs on non-debug, non-preempt * builds) * * (included on UP-non-debug builds:) * * linux/spinlock_api_up.h: * builds the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. */ All SMP and UP architectures are converted by this patch. arm, i386, ia64, ppc, ppc64, s390/s390x, x64 was build-tested via crosscompilers. m32r, mips, sh, sparc, have not been tested yet, but should be mostly fine. From: Grant Grundler <grundler@parisc-linux.org> Booted and lightly tested on a500-44 (64-bit, SMP kernel, dual CPU). Builds 32-bit SMP kernel (not booted or tested). I did not try to build non-SMP kernels. That should be trivial to fix up later if necessary. I converted bit ops atomic_hash lock to raw_spinlock_t. Doing so avoids some ugly nesting of linux/*.h and asm/*.h files. Those particular locks are well tested and contained entirely inside arch specific code. I do NOT expect any new issues to arise with them. If someone does ever need to use debug/metrics with them, then they will need to unravel this hairball between spinlocks, atomic ops, and bit ops that exist only because parisc has exactly one atomic instruction: LDCW (load and clear word). From: "Luck, Tony" <tony.luck@intel.com> ia64 fix Signed-off-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NArjan van de Ven <arjanv@infradead.org> Signed-off-by: NGrant Grundler <grundler@parisc-linux.org> Cc: Matthew Wilcox <willy@debian.org> Signed-off-by: NHirokazu Takata <takata@linux-m32r.org> Signed-off-by: NMikael Pettersson <mikpe@csd.uu.se> Signed-off-by: NBenoit Boissinot <benoit.boissinot@ens-lyon.org> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 09 9月, 2005 1 次提交
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由 David S. Miller 提交于
There were three changes necessary in order to allow sparc64 to use setup-res.c: 1) Sparc64 roots the PCI I/O and MEM address space using parent resources contained in the PCI controller structure. I'm actually surprised no other platforms do this, especially ones like Alpha and PPC{,64}. These resources get linked into the iomem/ioport tree when PCI controllers are probed. So the hierarchy looks like this: iomem --| PCI controller 1 MEM space --| device 1 device 2 etc. PCI controller 2 MEM space --| ... ioport --| PCI controller 1 IO space --| ... PCI controller 2 IO space --| ... You get the idea. The drivers/pci/setup-res.c code allocates using plain iomem_space and ioport_space as the root, so that wouldn't work with the above setup. So I added a pcibios_select_root() that is used to handle this. It uses the PCI controller struct's io_space and mem_space on sparc64, and io{port,mem}_resource on every other platform to keep current behavior. 2) quirk_io_region() is buggy. It takes in raw BUS view addresses and tries to use them as a PCI resource. pci_claim_resource() expects the resource to be fully formed when it gets called. The sparc64 implementation would do the translation but that's absolutely wrong, because if the same resource gets released then re-claimed we'll adjust things twice. So I fixed up quirk_io_region() to do the proper pcibios_bus_to_resource() conversion before passing it on to pci_claim_resource(). 3) I was mistakedly __init'ing the function methods the PCI controller drivers provide on sparc64 to implement some parts of these routines. This was, of course, easy to fix. So we end up with the following, and that nasty SPARC64 makefile ifdef in drivers/pci/Makefile is finally zapped. Signed-off-by: NDavid S. Miller <davem@davemloft.net> Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
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- 08 9月, 2005 7 次提交
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由 Stephen Rothwell 提交于
This patch just gathers together all the struct flock definitions except xtensa into asm-generic/fcntl.h. Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Stephen Rothwell 提交于
This patch puts the most popular of each open flag into asm-generic/fcntl.h and cleans up the arch files. Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Stephen Rothwell 提交于
This set of patches creates asm-generic/fcntl.h and consolidates as much as possible from the asm-*/fcntl.h files into it. This patch just gathers all the identical bits of the asm-*/fcntl.h files into asm-generic/fcntl.h. Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: NYoichi Yuasa <yuasa@hh.iij4u.or.jp> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Jesper Juhl 提交于
Remove the deprecated (and unused) verify_area() from various uaccess.h headers. Signed-off-by: NJesper Juhl <jesper.juhl@gmail.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Christoph Hellwig 提交于
unused and useless.. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 H. J. Lu 提交于
The size of auxiliary vector is fixed at 42 in linux/sched.h. But it isn't very obvious when looking at linux/elf.h. This patch adds AT_VECTOR_SIZE so that we can change it if necessary when a new vector is added. Because of include file ordering problems, doing this necessitated the extraction of the AT_* symbols into a standalone header file. Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Jakub Jelinek 提交于
ATM pthread_cond_signal is unnecessarily slow, because it wakes one waiter (which at least on UP usually means an immediate context switch to one of the waiter threads). This waiter wakes up and after a few instructions it attempts to acquire the cv internal lock, but that lock is still held by the thread calling pthread_cond_signal. So it goes to sleep and eventually the signalling thread is scheduled in, unlocks the internal lock and wakes the waiter again. Now, before 2003-09-21 NPTL was using FUTEX_REQUEUE in pthread_cond_signal to avoid this performance issue, but it was removed when locks were redesigned to the 3 state scheme (unlocked, locked uncontended, locked contended). Following scenario shows why simply using FUTEX_REQUEUE in pthread_cond_signal together with using lll_mutex_unlock_force in place of lll_mutex_unlock is not enough and probably why it has been disabled at that time: The number is value in cv->__data.__lock. thr1 thr2 thr3 0 pthread_cond_wait 1 lll_mutex_lock (cv->__data.__lock) 0 lll_mutex_unlock (cv->__data.__lock) 0 lll_futex_wait (&cv->__data.__futex, futexval) 0 pthread_cond_signal 1 lll_mutex_lock (cv->__data.__lock) 1 pthread_cond_signal 2 lll_mutex_lock (cv->__data.__lock) 2 lll_futex_wait (&cv->__data.__lock, 2) 2 lll_futex_requeue (&cv->__data.__futex, 0, 1, &cv->__data.__lock) # FUTEX_REQUEUE, not FUTEX_CMP_REQUEUE 2 lll_mutex_unlock_force (cv->__data.__lock) 0 cv->__data.__lock = 0 0 lll_futex_wake (&cv->__data.__lock, 1) 1 lll_mutex_lock (cv->__data.__lock) 0 lll_mutex_unlock (cv->__data.__lock) # Here, lll_mutex_unlock doesn't know there are threads waiting # on the internal cv's lock Now, I believe it is possible to use FUTEX_REQUEUE in pthread_cond_signal, but it will cost us not one, but 2 extra syscalls and, what's worse, one of these extra syscalls will be done for every single waiting loop in pthread_cond_*wait. We would need to use lll_mutex_unlock_force in pthread_cond_signal after requeue and lll_mutex_cond_lock in pthread_cond_*wait after lll_futex_wait. Another alternative is to do the unlocking pthread_cond_signal needs to do (the lock can't be unlocked before lll_futex_wake, as that is racy) in the kernel. I have implemented both variants, futex-requeue-glibc.patch is the first one and futex-wake_op{,-glibc}.patch is the unlocking inside of the kernel. The kernel interface allows userland to specify how exactly an unlocking operation should look like (some atomic arithmetic operation with optional constant argument and comparison of the previous futex value with another constant). It has been implemented just for ppc*, x86_64 and i?86, for other architectures I'm including just a stub header which can be used as a starting point by maintainers to write support for their arches and ATM will just return -ENOSYS for FUTEX_WAKE_OP. The requeue patch has been (lightly) tested just on x86_64, the wake_op patch on ppc64 kernel running 32-bit and 64-bit NPTL and x86_64 kernel running 32-bit and 64-bit NPTL. With the following benchmark on UP x86-64 I get: for i in nptl-orig nptl-requeue nptl-wake_op; do echo time elf/ld.so --library-path .:$i /tmp/bench; \ for j in 1 2; do echo ( time elf/ld.so --library-path .:$i /tmp/bench ) 2>&1; done; done time elf/ld.so --library-path .:nptl-orig /tmp/bench real 0m0.655s user 0m0.253s sys 0m0.403s real 0m0.657s user 0m0.269s sys 0m0.388s time elf/ld.so --library-path .:nptl-requeue /tmp/bench real 0m0.496s user 0m0.225s sys 0m0.271s real 0m0.531s user 0m0.242s sys 0m0.288s time elf/ld.so --library-path .:nptl-wake_op /tmp/bench real 0m0.380s user 0m0.176s sys 0m0.204s real 0m0.382s user 0m0.175s sys 0m0.207s The benchmark is at: http://sourceware.org/ml/libc-alpha/2005-03/txt00001.txt Older futex-requeue-glibc.patch version is at: http://sourceware.org/ml/libc-alpha/2005-03/txt00002.txt Older futex-wake_op-glibc.patch version is at: http://sourceware.org/ml/libc-alpha/2005-03/txt00003.txt Will post a new version (just x86-64 fixes so that the patch applies against pthread_cond_signal.S) to libc-hacker ml soon. Attached is the kernel FUTEX_WAKE_OP patch as well as a simple-minded testcase that will not test the atomicity of the operation, but at least check if the threads that should have been woken up are woken up and whether the arithmetic operation in the kernel gave the expected results. Acked-by: NIngo Molnar <mingo@redhat.com> Cc: Ulrich Drepper <drepper@redhat.com> Cc: Jamie Lokier <jamie@shareable.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: NYoichi Yuasa <yuasa@hh.iij4u.or.jp> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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