- 27 Mar, 2012 7 commits
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Hans de Goede authored
Some apps which use read() start the streaming through a call to poll(), this means that if another app has already claimed the device for streaming (through for example a s_fmt, or a reqbufs), that the poll should fail instead of getting passed through to vb2_poll. We only check for this when the app is polling for reads, so that ctrl events still work. Signed-off-by:
Hans de Goede <hdegoede@redhat.com> Signed-off-by:
Mauro Carvalho Chehab <mchehab@redhat.com>
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Hans Verkuil authored
The vb2_poll function now tests for events and sets POLLPRI accordingly. So there it is no longer necessary to test for it in the vivi driver. Signed-off-by:
Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by:
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Hans Verkuil authored
Signed-off-by:
Marek Szyprowski <m.szyprowski@samsung.com> Acked-by:
Pawel Osciak <pawel@osciak.com> Signed-off-by:
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Hans Verkuil authored
Signed-off-by:
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Hans Verkuil authored
Signed-off-by:
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Hans Verkuil authored
Signed-off-by:
Andy Walls <awalls@md.metrocast.net> Signed-off-by:
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Mauro Carvalho Chehab authored
* poll: (5970 commits) poll: add poll_requested_events() and poll_does_not_wait() functions crc32: select an algorithm via Kconfig crc32: add self-test code for crc32c crypto: crc32c should use library implementation crc32: bolt on crc32c crc32: add note about this patchset to crc32.c crc32: optimize loop counter for x86 crc32: add slice-by-8 algorithm to existing code crc32: make CRC_*_BITS definition correspond to actual bit counts crc32: fix mixing of endian-specific types crc32: miscellaneous cleanups crc32: simplify unit test code crc32: move long comment about crc32 fundamentals to Documentation/ crc32: remove two instances of trailing whitespaces checkpatch: check for quoted strings broken across lines checkpatch: whitespace - add/remove blank lines checkpatch: warn on use of yield() checkpatch: add --strict tests for braces, comments and casts checkpatch: add [] to type extensions checkpatch: high precedence operators do not require additional parentheses in #defines ...
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- 23 Mar, 2012 33 commits
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Hans Verkuil authored
In some cases the poll() implementation in a driver has to do different things depending on the events the caller wants to poll for. An example is when a driver needs to start a DMA engine if the caller polls for POLLIN, but doesn't want to do that if POLLIN is not requested but instead only POLLOUT or POLLPRI is requested. This is something that can happen in the video4linux subsystem among others. Unfortunately, the current epoll/poll/select implementation doesn't provide that information reliably. The poll_table_struct does have it: it has a key field with the event mask. But once a poll() call matches one or more bits of that mask any following poll() calls are passed a NULL poll_table pointer. Also, the eventpoll implementation always left the key field at ~0 instead of using the requested events mask. This was changed in eventpoll.c so the key field now contains the actual events that should be polled for as set by the caller. The solution to the NULL poll_table pointer is to set the qproc field to NULL in poll_table once poll() matches the events, not the poll_table pointer itself. That way drivers can obtain the mask through a new poll_requested_events inline. The poll_table_struct can still be NULL since some kernel code calls it internally (netfs_state_poll() in ./drivers/staging/pohmelfs/netfs.h). In that case poll_requested_events() returns ~0 (i.e. all events). Very rarely drivers might want to know whether poll_wait will actually wait. If another earlier file descriptor in the set already matched the events the caller wanted to wait for, then the kernel will return from the select() call without waiting. This might be useful information in order to avoid doing expensive work. A new helper function poll_does_not_wait() is added that drivers can use to detect this situation. This is now used in sock_poll_wait() in include/net/sock.h. This was the only place in the kernel that needed this information. Drivers should no longer access any of the poll_table internals, but use the poll_requested_events() and poll_does_not_wait() access functions instead. In order to enforce that the poll_table fields are now prepended with an underscore and a comment was added warning against using them directly. This required a change in unix_dgram_poll() in unix/af_unix.c which used the key field to get the requested events. It's been replaced by a call to poll_requested_events(). For qproc it was especially important to change its name since the behavior of that field changes with this patch since this function pointer can now be NULL when that wasn't possible in the past. Any driver accessing the qproc or key fields directly will now fail to compile. Some notes regarding the correctness of this patch: the driver's poll() function is called with a 'struct poll_table_struct *wait' argument. This pointer may or may not be NULL, drivers can never rely on it being one or the other as that depends on whether or not an earlier file descriptor in the select()'s fdset matched the requested events. There are only three things a driver can do with the wait argument: 1) obtain the key field: events = wait ? wait->key : ~0; This will still work although it should be replaced with the new poll_requested_events() function (which does exactly the same). This will now even work better, since wait is no longer set to NULL unnecessarily. 2) use the qproc callback. This could be deadly since qproc can now be NULL. Renaming qproc should prevent this from happening. There are no kernel drivers that actually access this callback directly, BTW. 3) test whether wait == NULL to determine whether poll would return without waiting. This is no longer sufficient as the correct test is now wait == NULL || wait->_qproc == NULL. However, the worst that can happen here is a slight performance hit in the case where wait != NULL and wait->_qproc == NULL. In that case the driver will assume that poll_wait() will actually add the fd to the set of waiting file descriptors. Of course, poll_wait() will not do that since it tests for wait->_qproc. This will not break anything, though. There is only one place in the whole kernel where this happens (sock_poll_wait() in include/net/sock.h) and that code will be replaced by a call to poll_does_not_wait() in the next patch. Note that even if wait->_qproc != NULL drivers cannot rely on poll_wait() actually waiting. The next file descriptor from the set might match the event mask and thus any possible waits will never happen. Signed-off-by:
Jonathan Corbet <corbet@lwn.net> Reviewed-by:
Al Viro <viro@zeniv.linux.org.uk> Cc: Davide Libenzi <davidel@xmailserver.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Darrick J. Wong authored
Allow the kernel builder to choose a crc32* algorithm for the kernel. Signed-off-by:
Darrick J. Wong <djwong@us.ibm.com> Cc: Bob Pearson <rpearson@systemfabricworks.com> Signed-off-by:
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Darrick J. Wong authored
Add self-test code for crc32c. Signed-off-by:
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Darrick J. Wong authored
Since lib/crc32.c now provides crc32c, remove the software implementation here and call the library function instead. Signed-off-by:
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Darrick J. Wong authored
Reuse the existing crc32 code to stamp out a crc32c implementation. Signed-off-by:
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Bob Pearson authored
Add a comment at the top of crc32.c [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
Bob Pearson <rpearson@systemfabricworks.com> Signed-off-by:
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Bob Pearson authored
Add two changes that improve the performance of x86 systems 1. replace main loop with incrementing counter this change improves the performance of the selftest by about 5-6% on Nehalem CPUs. The apparent reason is that the compiler can use the loop index to perform an indexed memory access. This is reported to make the performance of PowerPC CPUs to get worse. 2. replace the rem_len loop with incrementing counter this change improves the performance of the selftest, which has more than the usual number of occurances, by about 1-2% on x86 CPUs. In actual work loads the length is most often a multiple of 4 bytes and this code does not get executed as often if at all. Again this change is reported to make the performance of PowerPC get worse. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
Add slicing-by-8 algorithm to the existing slicing-by-4 algorithm. This consists of: - extend largest BITS size from 32 to 64 - extend tables from tab[4][256] to up to tab[8][256] - Add code for inner loop. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
crc32.c provides a choice of one of several algorithms for computing the LSB and LSB versions of the CRC32 checksum based on the parameters CRC_LE_BITS and CRC_BE_BITS. In the original version the values 1, 2, 4 and 8 respectively selected versions of the alrogithm that computed the crc 1, 2, 4 and 32 bits as a time. This patch series adds a new version that computes the CRC 64 bits at a time. To make things easier to understand the parameter has been reinterpreted to actually stand for the number of bits processed in each step of the algorithm so that the old value 8 has been replaced with the value 32. This also allows us to add in a widely used crc algorithm that computes the crc 8 bits at a time called the Sarwate algorithm. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
crc32.c in its original version freely mixed u32, __le32 and __be32 types which caused warnings from sparse with __CHECK_ENDIAN__. This patch fixes these by forcing the types to u32. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
Misc cleanup of lib/crc32.c and related files. - remove unnecessary header files. - straighten out some convoluted ifdef's - rewrite some references to 2 dimensional arrays as 1 dimensional arrays to make them correct. I.e. replace tab[i] with tab[0][i]. - a few trivial whitespace changes - fix a warning in gen_crc32tables.c caused by a mismatch in the type of the pointer passed to output table. Since the table is only used at kernel compile time, it is simpler to make the table big enough to hold the largest column size used. One cannot make the column size smaller in output_table because it has to be used by both the le and be tables and they can have different column sizes. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
Replace the unit test provided in crc32.c, which doesn't have a makefile and doesn't compile with current headers, with a simpler self test routine that also gives a measure of performance and runs at module init time. The self test option can be enabled through a configuration option CONFIG_CRC32_SELFTEST. The test stresses the pre and post loops and is thus not very realistic since actual uses will likely have addresses and lengths that are at least 4 byte aligned. However, the main loop is long enough so that the performance is dominated by that loop. The expected values for crc32_le and crc32_be were generated with the original version of crc32.c using CRC_BITS_LE = 8 and CRC_BITS_BE = 8. These values were then used to check all the values of the BITS parameters in both the original and new versions. The performance results show some variability from run to run in spite of attempts to both warm the cache and reduce the amount of OS noise by limiting interrutps during the test. To get comparable results and to analyse options wrt performance the best time reported over a small sample of runs has been taken. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by:
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Bob Pearson authored
Move a long comment from lib/crc32.c to Documentation/crc32.txt where it will more likely get read. Edited the resulting document to add an explanation of the slicing-by-n algorithm. [djwong@us.ibm.com: minor changelog tweaks] [akpm@linux-foundation.org: fix typo, per George] Signed-off-by:
George Spelvin <linux@horizon.com> Signed-off-by:
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Bob Pearson authored
This patchset (re)uses Bob Pearson's crc32 slice-by-8 code to stamp out a software crc32c implementation. It removes the crc32c implementation in crypto/ in favor of using the stamped-out one in lib/. There is also a change to Kconfig so that the kernel builder can pick an implementation best suited for the hardware. The motivation for this patchset is that I am working on adding full metadata checksumming to ext4. As far as performance impact of adding checksumming goes, I see nearly no change with a standard mail server ffsb simulation. On a test that involves only file creation and deletion and extent tree writes, I see a drop of about 50 pcercent with the current kernel crc32c implementation; this improves to a drop of about 20 percent with the enclosed crc32c code. When metadata is usually a small fraction of total IO, this new implementation doesn't help much because metadata is usually a small fraction of total IO. However, when we are doing IO that is almost all metadata (such as rm -rf'ing a tree), then this patch speeds up the operation substantially. Incidentally, given that iscsi, sctp, and btrfs also use crc32c, this patchset should improve their speed as well. I have not yet quantified that, however. This latest submission combines Bob's patches from late August 2011 with mine so that they can be one coherent patch set. Please excuse my inability to combine some of the patches; I've been advised to leave Bob's patches alone and build atop them instead. :/ Since the last posting, I've also collected some crc32c test results on a bunch of different x86/powerpc/sparc platforms. The results can be viewed here: http://goo.gl/sgt3i ; the "crc32-kern-le" and "crc32c" columns describe the performance of the kernel's current crc32 and crc32c software implementations. The "crc32c-by8-le" column shows crc32c performance with this patchset applied. I expect crc32 performance to be roughly the same. The two _boost columns at the right side of the spreadsheet shows how much faster the new implementation is over the old one. As you can see, crc32 rises substantially, and crc32c experiences a huge increase. This patch: - remove trailing whitespace from lib/crc32.c - remove trailing whitespace from lib/crc32defs.h [djwong@us.ibm.com: changelog tweaks] Signed-off-by:
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Josh Triplett authored
checkpatch already makes an exception to the 80-column rule for quoted strings, and Documentation/CodingStyle recommends not splitting quoted strings across lines, because it breaks the ability to grep for the string. Rather than just permitting this, actively warn about quoted strings split across lines. Test case: void context(void) { struct { unsigned magic; const char *strdata; } foo[] = { { 42, "these strings" "do not produce warnings" }, { 256, "though perhaps" "they should" }, }; pr_err("this string" " should produce a warning\n"); pr_err("this multi-line string\n" "should not produce a warning\n"); asm ("this asm\n\t" "should not produce a warning"); } Results of checkpatch on that test case: WARNING: quoted string split across lines + " should produce a warning\n"); total: 0 errors, 1 warnings, 15 lines checked Signed-off-by:Josh Triplett <josh@joshtriplett.org> Acked-by:
Joe Perches <joe@perches.com> Cc: Andy Whitcroft <apw@canonical.com> Signed-off-by:
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Joe Perches authored
Add blank lines between a few tests, remove an extraneous one. Signed-off-by:
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Joe Perches authored
Using yield() is generally wrong. Warn on its use. Signed-off-by:
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Joe Perches authored
Add some more subjective --strict tests. Add a test for block comments that start with a blank line followed only by a line with just the comment block initiator. Prefer a blank line followed by /* comment... Add a test for unnecessary spaces after a cast. Add a test for symmetric uses of braces in if/else blocks. If one branch needs braces, then all branches should use braces. Signed-off-by:
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Andy Whitcroft authored
Add [] to a type extensions. Fixes false positives on: .attrs = (struct attribute *[]) { Signed-off-by:Andy Whitcroft <apw@canonical.com> Cc: Joe Perches <joe@perches.com> Signed-off-by:
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Andy Whitcroft authored
With any very high precedence operator it is not necessary to enforce additional parentheses around simple negated expressions. This prevents us requesting further perentheses around the following: #define PMEM_IS_FREE(id, index) !(pmem[id].bitmap[index].allocated) For now add logical and bitwise not and unary minus. Signed-off-by: -
Andy Whitcroft authored
Adjacent strings indicate concatentation, therefore look at identifiers directly adjacent to literal strings as strings too. This allows us to better detect the form below and accept it as a simple constant: #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt Signed-off-by: -
Andy Whitcroft authored
Signed-off-by:
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Andy Whitcroft authored
Handle the [ A ... B ] form deeper into a definition, for example: static const unsigned char pci_irq_swizzle[2][PCI_MAX_DEVICES] = { {0, 0, 0, 0, 0, 0, 0, 27, 27, [9 ... PCI_MAX_DEVICES - 1] = 0 }, {0, 0, 0, 0, 0, 0, 0, 29, 29, [9 ... PCI_MAX_DEVICES - 1] = 0 }, }; Reported-by:Marek Vasut <marek.vasut@gmail.com> Signed-off-by:
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Artem Bityutskiy authored
Fix checkpatch.pl when both -q and --ignore are given and prevents it from printing a NOTE: Ignored message types: blah messages. E.g., if I use -q --ignore PREFER_PACKED,PREFER_ALIGNED, i see: NOTE: Ignored message types: PREFER_ALIGNED PREFER_PACKED It makes no sense to print this when -q is given. Signed-off-by:
Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Joe Perches <joe@perches.com> Signed-off-by:
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Joe Perches authored
Argument alignment across multiple lines should match the open parenthesis. Logical continuations should be at the end of the previous line, not the start of a new line. These are not required by CodingStyle so make the tests active only when using --strict. Improved by some examples from Bruce Allen. Signed-off-by:
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Joe Perches authored
It's equivalent to __printf, so prefer __scanf. Signed-off-by:
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Xiao Guangrong authored
Introduce prio_set_parent() to abstract the operation which is used to attach the node to its parent. Signed-off-by:
Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Signed-off-by:
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Xiao Guangrong authored
In current code, the deleted-node is recorded from first to last, actually, we can directly attach these node on 'node' we will insert as the left child, it can let the code more readable. Signed-off-by:
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Xiao Guangrong authored
Introduce iter_walk_down()/iter_walk_up() to remove the common code between prio_tree_left() and prio_tree_right(). Signed-off-by:
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Xiao Guangrong authored
Remove the code since 'node' has already been initialized in the begin of the function Signed-off-by:
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Akinobu Mita authored
- Generate a 64-bit pattern more efficiently memchr_inv needs to generate a 64-bit pattern filled with a target character. The operation can be done by more efficient way. - Don't call the slow check_bytes() if the memory area is 64-bit aligned memchr_inv compares contiguous 64-bit words with the 64-bit pattern as much as possible. The outside of the region is checked by check_bytes() that scans for each byte. Unfortunately, the first 64-bit word is unexpectedly scanned by check_bytes() even if the memory area is aligned to a 64-bit boundary. Both changes were originally suggested by Eric Dumazet. Signed-off-by:
Akinobu Mita <akinobu.mita@gmail.com> Suggested-by:
Eric Dumazet <eric.dumazet@gmail.com> Cc: Brian Norris <computersforpeace@gmail.com> Signed-off-by:
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Bryan Wu authored
After moving some core functions to led-core.c, led-class.c can be built as module again. Signed-off-by:
Bryan Wu <bryan.wu@canonical.com> Acked-by:
Richard Purdie <richard.purdie@linuxfoundation.org> Acked-by:
Linus Walleij <linus.walleij@linaro.org> Signed-off-by:
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Axel Lin authored
Improve the readability by moving the code setting gen_config to one place. [akpm@linux-foundation.org: fix some patch skew] Signed-off-by:
Axel Lin <axel.lin@gmail.com> Cc: Shreshtha Kumar Sahu <shreshthakumar.sahu@stericsson.com> Cc: "Milo(Woogyom) Kim" <milo.kim@ti.com> Cc: Richard Purdie <rpurdie@rpsys.net> Acked-by:
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