- 11 Oct, 2016 40 commits
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Michael Kerrisk (man-pages) authored
Replace an 'if' block that covers most of the code in this function with a 'goto'. This makes the code a little simpler to read, and also simplifies the next patch (fix limit checking in alloc_pipe_info()) Link: http://lkml.kernel.org/r/aef030c1-0257-98a9-4988-186efa48530c@gmail.comSigned-off-by:
Michael Kerrisk <mtk.manpages@gmail.com> Reviewed-by:
Vegard Nossum <vegard.nossum@oracle.com> Cc: Willy Tarreau <w@1wt.eu> Cc: <socketpair@gmail.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Jens Axboe <axboe@fb.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Michael Kerrisk (man-pages) authored
The limit checking in pipe_set_size() (used by fcntl(F_SETPIPE_SZ)) has the following problems: (1) When increasing the pipe capacity, the checks against the limits in /proc/sys/fs/pipe-user-pages-{soft,hard} are made against existing consumption, and exclude the memory required for the increased pipe capacity. The new increase in pipe capacity can then push the total memory used by the user for pipes (possibly far) over a limit. This can also trigger the problem described next. (2) The limit checks are performed even when the new pipe capacity is less than the existing pipe capacity. This can lead to problems if a user sets a large pipe capacity, and then the limits are lowered, with the result that the user will no longer be able to decrease the pipe capacity. (3) As currently implemented, accounting and checking against the limits is done as follows: (a) Test whether the user has exceeded the limit. (b) Make new pipe buffer allocation. (c) Account new allocation against the limits. This is racey. Multiple processes may pass point (a) simultaneously, and then allocate pipe buffers that are accounted for only in step (c). The race means that the user's pipe buffer allocation could be pushed over the limit (by an arbitrary amount, depending on how unlucky we were in the race). [Thanks to Vegard Nossum for spotting this point, which I had missed.] This patch addresses the above problems as follows: * Perform checks against the limits only when increasing a pipe's capacity; an unprivileged user can always decrease a pipe's capacity. * Alter the checks against limits to include the memory required for the new pipe capacity. * Re-order the accounting step so that it precedes the buffer allocation. If the accounting step determines that a limit has been reached, revert the accounting and cause the operation to fail. The program below can be used to demonstrate problems 1 and 2, and the effect of the fix. The program takes one or more command-line arguments. The first argument specifies the number of pipes that the program should create. The remaining arguments are, alternately, pipe capacities that should be set using fcntl(F_SETPIPE_SZ), and sleep intervals (in seconds) between the fcntl() operations. (The sleep intervals allow the possibility to change the limits between fcntl() operations.) Problem 1 ========= Using the test program on an unpatched kernel, we first set some limits: # echo 0 > /proc/sys/fs/pipe-user-pages-soft # echo 1000000000 > /proc/sys/fs/pipe-max-size # echo 10000 > /proc/sys/fs/pipe-user-pages-hard # 40.96 MB Then show that we can set a pipe with capacity (100MB) that is over the hard limit # sudo -u mtk ./test_F_SETPIPE_SZ 1 100000000 Initial pipe capacity: 65536 Loop 1: set pipe capacity to 100000000 bytes F_SETPIPE_SZ returned 134217728 Now set the capacity to 100MB twice. The second call fails (which is probably surprising to most users, since it seems like a no-op): # sudo -u mtk ./test_F_SETPIPE_SZ 1 100000000 0 100000000 Initial pipe capacity: 65536 Loop 1: set pipe capacity to 100000000 bytes F_SETPIPE_SZ returned 134217728 Loop 2: set pipe capacity to 100000000 bytes Loop 2, pipe 0: F_SETPIPE_SZ failed: fcntl: Operation not permitted With a patched kernel, setting a capacity over the limit fails at the first attempt: # echo 0 > /proc/sys/fs/pipe-user-pages-soft # echo 1000000000 > /proc/sys/fs/pipe-max-size # echo 10000 > /proc/sys/fs/pipe-user-pages-hard # sudo -u mtk ./test_F_SETPIPE_SZ 1 100000000 Initial pipe capacity: 65536 Loop 1: set pipe capacity to 100000000 bytes Loop 1, pipe 0: F_SETPIPE_SZ failed: fcntl: Operation not permitted There is a small chance that the change to fix this problem could break user-space, since there are cases where fcntl(F_SETPIPE_SZ) calls that previously succeeded might fail. However, the chances are small, since (a) the pipe-user-pages-{soft,hard} limits are new (in 4.5), and the default soft/hard limits are high/unlimited. Therefore, it seems warranted to make these limits operate more precisely (and behave more like what users probably expect). Problem 2 ========= Running the test program on an unpatched kernel, we first set some limits: # getconf PAGESIZE 4096 # echo 0 > /proc/sys/fs/pipe-user-pages-soft # echo 1000000000 > /proc/sys/fs/pipe-max-size # echo 10000 > /proc/sys/fs/pipe-user-pages-hard # 40.96 MB Now perform two fcntl(F_SETPIPE_SZ) operations on a single pipe, first setting a pipe capacity (10MB), sleeping for a few seconds, during which time the hard limit is lowered, and then set pipe capacity to a smaller amount (5MB): # sudo -u mtk ./test_F_SETPIPE_SZ 1 10000000 15 5000000 & [1] 748 # Initial pipe capacity: 65536 Loop 1: set pipe capacity to 10000000 bytes F_SETPIPE_SZ returned 16777216 Sleeping 15 seconds # echo 1000 > /proc/sys/fs/pipe-user-pages-hard # 4.096 MB # Loop 2: set pipe capacity to 5000000 bytes Loop 2, pipe 0: F_SETPIPE_SZ failed: fcntl: Operation not permitted In this case, the user should be able to lower the limit. With a kernel that has the patch below, the second fcntl() succeeds: # echo 0 > /proc/sys/fs/pipe-user-pages-soft # echo 1000000000 > /proc/sys/fs/pipe-max-size # echo 10000 > /proc/sys/fs/pipe-user-pages-hard # sudo -u mtk ./test_F_SETPIPE_SZ 1 10000000 15 5000000 & [1] 3215 # Initial pipe capacity: 65536 # Loop 1: set pipe capacity to 10000000 bytes F_SETPIPE_SZ returned 16777216 Sleeping 15 seconds # echo 1000 > /proc/sys/fs/pipe-user-pages-hard # Loop 2: set pipe capacity to 5000000 bytes F_SETPIPE_SZ returned 8388608 8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x--- /* test_F_SETPIPE_SZ.c (C) 2016, Michael Kerrisk; licensed under GNU GPL version 2 or later Test operation of fcntl(F_SETPIPE_SZ) for setting pipe capacity and interactions with limits defined by /proc/sys/fs/pipe-* files. */ #define _GNU_SOURCE #include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <unistd.h> int main(int argc, char *argv[]) { int (*pfd)[2]; int npipes; int pcap, rcap; int j, p, s, stime, loop; if (argc < 2) { fprintf(stderr, "Usage: %s num-pipes " "[pipe-capacity sleep-time]...\n", argv[0]); exit(EXIT_FAILURE); } npipes = atoi(argv[1]); pfd = calloc(npipes, sizeof (int [2])); if (pfd == NULL) { perror("calloc"); exit(EXIT_FAILURE); } for (j = 0; j < npipes; j++) { if (pipe(pfd[j]) == -1) { fprintf(stderr, "Loop %d: pipe() failed: ", j); perror("pipe"); exit(EXIT_FAILURE); } } printf("Initial pipe capacity: %d\n", fcntl(pfd[0][0], F_GETPIPE_SZ)); for (j = 2; j < argc; j += 2 ) { loop = j / 2; pcap = atoi(argv[j]); printf(" Loop %d: set pipe capacity to %d bytes\n", loop, pcap); for (p = 0; p < npipes; p++) { s = fcntl(pfd[p][0], F_SETPIPE_SZ, pcap); if (s == -1) { fprintf(stderr, " Loop %d, pipe %d: F_SETPIPE_SZ " "failed: ", loop, p); perror("fcntl"); exit(EXIT_FAILURE); } if (p == 0) { printf(" F_SETPIPE_SZ returned %d\n", s); rcap = s; } else { if (s != rcap) { fprintf(stderr, " Loop %d, pipe %d: F_SETPIPE_SZ " "unexpected return: %d\n", loop, p, s); exit(EXIT_FAILURE); } } stime = (j + 1 < argc) ? atoi(argv[j + 1]) : 0; if (stime > 0) { printf(" Sleeping %d seconds\n", stime); sleep(stime); } } } exit(EXIT_SUCCESS); } 8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x--- Patch history: v2 * Switch order of test in 'if' statement to avoid function call (to capability()) in normal path. [This is a fix to a preexisting wart in the code. Thanks to Willy Tarreau] * Perform (size > pipe_max_size) check before calling account_pipe_buffers(). [Thanks to Vegard Nossum] Quoting Vegard: The potential problem happens if the user passes a very large number which will overflow pipe->user->pipe_bufs. On 32-bit, sizeof(int) == sizeof(long), so if they pass arg = INT_MAX then round_pipe_size() returns INT_MAX. Although it's true that the accounting is done in terms of pages and not bytes, so you'd need on the order of (1 << 13) = 8192 processes hitting the limit at the same time in order to make it overflow, which seems a bit unlikely. (See https://lkml.org/lkml/2016/8/12/215 for another discussion on the limit checking) Link: http://lkml.kernel.org/r/1e464945-536b-2420-798b-e77b9c7e8593@gmail.comSigned-off-by: -
Michael Kerrisk (man-pages) authored
This is a preparatory patch for following work. account_pipe_buffers() performs accounting in the 'user_struct'. There is no need to pass a pointer to a 'pipe_inode_info' struct (which is then dereferenced to obtain a pointer to the 'user' field). Instead, pass a pointer directly to the 'user_struct'. This change is needed in preparation for a subsequent patch that the fixes the limit checking in alloc_pipe_info() (and the resulting code is a little more logical). Link: http://lkml.kernel.org/r/7277bf8c-a6fc-4a7d-659c-f5b145c981ab@gmail.comSigned-off-by:
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Michael Kerrisk (man-pages) authored
This is a preparatory patch for following work. Move the F_SETPIPE_SZ limit-checking logic from pipe_fcntl() into pipe_set_size(). This simplifies the code a little, and allows for reworking required in a later patch that fixes the limit checking in pipe_set_size() Link: http://lkml.kernel.org/r/3701b2c5-2c52-2c3e-226d-29b9deb29b50@gmail.comSigned-off-by:
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Michael Kerrisk (man-pages) authored
Patch series "pipe: fix limit handling", v2. When changing a pipe's capacity with fcntl(F_SETPIPE_SZ), various limits defined by /proc/sys/fs/pipe-* files are checked to see if unprivileged users are exceeding limits on memory consumption. While documenting and testing the operation of these limits I noticed that, as currently implemented, these checks have a number of problems: (1) When increasing the pipe capacity, the checks against the limits in /proc/sys/fs/pipe-user-pages-{soft,hard} are made against existing consumption, and exclude the memory required for the increased pipe capacity. The new increase in pipe capacity can then push the total memory used by the user for pipes (possibly far) over a limit. This can also trigger the problem described next. (2) The limit checks are performed even when the new pipe capacity is less than the existing pipe capacity. This can lead to problems if a user sets a large pipe capacity, and then the limits are lowered, with the result that the user will no longer be able to decrease the pipe capacity. (3) As currently implemented, accounting and checking against the limits is done as follows: (a) Test whether the user has exceeded the limit. (b) Make new pipe buffer allocation. (c) Account new allocation against the limits. This is racey. Multiple processes may pass point (a) simultaneously, and then allocate pipe buffers that are accounted for only in step (c). The race means that the user's pipe buffer allocation could be pushed over the limit (by an arbitrary amount, depending on how unlucky we were in the race). [Thanks to Vegard Nossum for spotting this point, which I had missed.] This patch series addresses these three problems. This patch (of 8): This is a minor preparatory patch. After subsequent patches, round_pipe_size() will be called from pipe_set_size(), so place round_pipe_size() above pipe_set_size(). Link: http://lkml.kernel.org/r/91a91fdb-a959-ba7f-b551-b62477cc98a1@gmail.comSigned-off-by: -
Tomohiro Kusumi authored
cmd part of this struct is the same as an index of itself within _ioctls[]. In fact this cmd is unused, so we can drop this part. Link: http://lkml.kernel.org/r/20160831033414.9910.66697.stgit@pluto.themaw.netSigned-off-by:
Tomohiro Kusumi <kusumi.tomohiro@gmail.com> Signed-off-by:
Ian Kent <raven@themaw.net> Signed-off-by:
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Tomohiro Kusumi authored
Having this in autofs_i.h gives illusion that uncommenting this enables pr_debug(), but it doesn't enable all the pr_debug() in autofs because inclusion order matters. XFS has the same DEBUG macro in its core header fs/xfs/xfs.h, however XFS seems to have a rule to include this prior to other XFS headers as well as kernel headers. This is not the case with autofs, and DEBUG could be enabled via Makefile, so autofs should just get rid of this comment to make the code less confusing. It's a comment, so there is literally no functional difference. Link: http://lkml.kernel.org/r/20160831033409.9910.77067.stgit@pluto.themaw.netSigned-off-by:
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Ian Kent authored
Since linux/auto_dev-ioctl.h wasn't included in include/linux/Kbuild it wasn't moved to uapi/linux as part of the uapi series. Link: http://lkml.kernel.org/r/20160812024901.12352.10984.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
linux/limits.h should be included by uapi instead of linux/auto_fs.h so as not to cause compile error in userspace. # cat << EOF > ./test1.c > #include <stdio.h> > #include <linux/auto_fs.h> > int main(void) { > return 0; > } > EOF # gcc -Wall -g ./test1.c In file included from ./test1.c:2:0: /usr/include/linux/auto_fs.h:54:12: error: 'NAME_MAX' undeclared here (not in a function) char name[NAME_MAX+1]; ^ Link: http://lkml.kernel.org/r/20160812024856.12352.24092.stgit@pluto.themaw.netSigned-off-by:Ian Kent <ikent@redhat.com> Signed-off-by:
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Tomohiro Kusumi authored
All other warnings use "cmd(0x%08x)" and this is the only one with "cmd(%d)". (below comes from my userspace debug program, but not automount daemon) [ 1139.905676] autofs4:pid:1640:check_dev_ioctl_version: ioctl control interface version mismatch: kernel(1.0), user(0.0), cmd(-1072131215) Link: http://lkml.kernel.org/r/20160812024851.12352.75458.stgit@pluto.themaw.netSigned-off-by:
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Ian Kent authored
No functional changes, based on the following justification. 1. Make the code more consistent using the ioctl vector _ioctls[], rather than assigning NULL only for this ioctl command. 2. Remove goto done; for better maintainability in the long run. 3. The existing code is based on the fact that validate_dev_ioctl() sets ioctl version for any command, but AUTOFS_DEV_IOCTL_VERSION_CMD should explicitly set it regardless of the default behavior. Link: http://lkml.kernel.org/r/20160812024846.12352.9885.stgit@pluto.themaw.netSigned-off-by:
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Ian Kent authored
The count of miscellaneous device ioctls in fs/autofs4/autofs_i.h is wrong. The number of ioctls is the difference between AUTOFS_DEV_IOCTL_VERSION_CMD and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD (14) not the difference between AUTOFS_IOC_COUNT and 11 (21). [kusumi.tomohiro@gmail.com: fix typo that made the count macro negative] Link: http://lkml.kernel.org/r/20160831033420.9910.16809.stgit@pluto.themaw.net Link: http://lkml.kernel.org/r/20160812024841.12352.11975.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
This isn't a return value, so change the message to indicate the status is the result of may_umount(). (or locate pr_debug() after put_user() with the same message) Link: http://lkml.kernel.org/r/20160812024836.12352.74628.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
Sync with changes made by commit 730c9eec ("autofs4: improve parameter usage") which introduced an union for various ioctl commands instead of having statically named arg1,2. This commit simply replaces arg1,2 with the corresponding fields without changing semantics. Link: http://lkml.kernel.org/r/20160812024831.12352.24667.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
The explanation on how ioctl handles devid seems incorrect. Userspace who calls this ioctl has no input regarding devid, and ioctl implementation retrieves devid via superblock. Link: http://lkml.kernel.org/r/20160812024825.12352.13486.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
This macro was never used by neither kernel nor userspace, and also doesn't represent "devid length" in bytes. (unless it was added to mean something else). Link: http://lkml.kernel.org/r/20160812024820.12352.21210.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
Returning -ENOTTY here fails to free dynamically allocated param. Link: http://lkml.kernel.org/r/20160812024815.12352.69153.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
These two were left from commit aa55ddf3 ("autofs4: remove unused ioctls") which removed unused ioctls. Link: http://lkml.kernel.org/r/20160812024810.12352.96377.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
kfree dentry data allocated by autofs4_new_ino() with autofs4_free_ino() instead of raw kfree. (since we have the interface to free autofs_info*) This patch was modified to remove the need to set the dentry info field to NULL dew to a change in the previous patch. Link: http://lkml.kernel.org/r/20160812024805.12352.43650.stgit@pluto.themaw.netSigned-off-by:
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Ian Kent authored
The inode allocation failure case in autofs4_dir_symlink() frees the autofs dentry info of the dentry without setting ->d_fsdata to NULL. That could lead to a double free so just get rid of the free and leave it to ->d_release(). Link: http://lkml.kernel.org/r/20160812024759.12352.10653.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
It's invalid if the given mode is neither dir nor link, so warn on else case. Link: http://lkml.kernel.org/r/20160812024754.12352.8536.stgit@pluto.themaw.netSigned-off-by:
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Ian Kent authored
Somewhere along the line the error handling gotos have become incorrect. Link: http://lkml.kernel.org/r/20160812024749.12352.15100.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
This patch does what the below comment says. It could be and it's considered better to do this first before various functions get called during initialization. /* Couldn't this be tested earlier? */ Link: http://lkml.kernel.org/r/20160812024744.12352.43075.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
autofs4_kill_sb() doesn't need to be declared as extern, and no other functions in .h are explicitly declared as extern. Link: http://lkml.kernel.org/r/20160812024739.12352.99354.stgit@pluto.themaw.netSigned-off-by:
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Tomohiro Kusumi authored
plus minor whitespace fixes. Link: http://lkml.kernel.org/r/20160812024734.12352.17122.stgit@pluto.themaw.netSigned-off-by:
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Christoph Hellwig authored
asm-generic headers are generic implementations for architecture specific code and should not be included by common code. Thus use the asm/ version of sections.h to get at the linker sections. Link: http://lkml.kernel.org/r/1473602302-6208-1-git-send-email-hch@lst.deSigned-off-by:
Christoph Hellwig <hch@lst.de> Acked-by:
Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by:
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Joe Perches authored
The function calls with octal permissions commonly span multiple lines. The current test is line oriented and fails to find some matches. Make the test use the $stat variable instead of the $line variable to span multiple lines. Also add a few functions to the known functions with permissions list. Move the SYMBOLIC_PERMS test to a separate section to find all the S_<FOO> permissions in any form not just those that have specific function names. This can now find and fix permissions uses like: .mode = S_<FOO> | S_<BAR>; Link: http://lkml.kernel.org/r/b51bab60530912aae4ac420119d465c5b206f19f.1475030406.git.joe@perches.comSigned-off-by:Joe Perches <joe@perches.com> Tested-by:
Ramiro Oliveira <roliveir@synopsys.com> Signed-off-by:
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Joe Perches authored
Function definitions without identifiers like int foo(int) are not preferred. Emit a warning when they occur. Link: http://lkml.kernel.org/r/94fe6378504745991b650f48fc92bb4648f25706.1474925354.git.joe@perches.comSigned-off-by:
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Joe Perches authored
It is possible for a multiple line macro definition to have a false positive report when an argument is used on a line after a continuation \. This line might have a leading '+' as the initial character that could be confused by checkpatch as an operator. Avoid the leading character on multiple line macro definitions. Link: http://lkml.kernel.org/r/60229d13399f9b6509db5a32e30d4c16951a60cd.1473836073.git.joe@perches.comSigned-off-by:
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Joe Perches authored
Add a test for macro arguents that have a non-comma leading or trailing operator where the argument isn't parenthesized to avoid possible precedence issues. Link: http://lkml.kernel.org/r/47715508972f8d786f435e583ff881dbeee3a114.1473745855.git.joe@perches.comSigned-off-by:
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Joe Perches authored
If a macro argument is used multiple times in the macro definition, the macro argument may have an unexpected side-effect. Add a test (MACRO_ARG_REUSE) for that condition which is only emitted with command-line option --strict. Link: http://lkml.kernel.org/r/b6d67a87cafcafd15499e91780dc63b15dec0aa0.1473744906.git.joe@perches.comSigned-off-by:
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Joe Perches authored
An "uninitialized value" is emitted when a block comment starts on the same line as a statement. Fix this and make the test use a little fewer cpu cycles too. Link: http://lkml.kernel.org/r/3c9993320c2182d37f53ac540878cfef59c3f62d.1473365956.git.joe@perches.comSigned-off-by:
Charlemagne Lasse <charlemagnelasse@gmail.com> Signed-off-by:
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Joe Perches authored
Adding -f to the get_maintainer.pl invocation means git isn't invoked by get_maintainer.pl for known filenames. This reduces the overall time to run checkpatch. Link: http://lkml.kernel.org/r/22991e3a295aeb399b43af0478b6e5809106ccee.1472684066.git.joe@perches.comSigned-off-by:
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Joe Perches authored
Using const is generally a good idea. Julia Lawall has created a list of always const and almost always const structs in the kernel sources. Link: https://lkml.org/lkml/2016/8/28/95 Add the most frequently used (> 50 cases) that are almost always or always const. Link: http://lkml.kernel.org/r/1e16020f8027654db0095bbfbcc11da51025365c.1472664220.git.joe@perches.comSigned-off-by:
Kees Cook <keescook@chromium.org> Cc: Julia Lawall <julia.lawall@lip6.fr> Cc: Andy Whitcroft <apw@canonical.com> Signed-off-by:
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Joe Perches authored
Make it easier to add new structs that should be const. Link: http://lkml.kernel.org/r/e5a8da43e7c11525bafbda1ca69a8323614dd942.1472664220.git.joe@perches.comSigned-off-by:
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Joe Perches authored
< sigh > Comment these tests out. These are just too enticing to people that don't verify that both source and dest addresses really must be __aligned(2). It helps make Dan Carpenter happy too. Link: http://lkml.kernel.org/r/dc32ec66d24647f4cdf824c8dfbbc59aa7ce7b7d.1472665676.git.joe@perches.comSigned-off-by:
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Joe Perches authored
Warn when block comments are not aligned on the * /* * block comment, no warning */ /* * block comment, emit warning */ Link: http://lkml.kernel.org/r/edb57bd330adfe024b95ec2a807d4aa7f0c8b112.1472261299.git.joe@perches.comSigned-off-by:
Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by:
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Joe Perches authored
S_<FOO> uses should be avoided where octal is more intelligible. Linus didst say: : It's *much* easier to parse and understand the octal numbers, while the : symbolic macro names are just random line noise and hard as hell to : understand. You really have to think about it. : : So we should rather go the other way: convert existing bad symbolic : permission bit macro use to just use the octal numbers. : : The symbolic names are good for the *other* bits (ie sticky bit, and the : inode mode _type_ numbers etc), but for the permission bits, the symbolic : names are just insane crap. Nobody sane should ever use them. Not in the : kernel, not in user space. (http://lkml.kernel.org/r/CA+55aFw5v23T-zvDZp-MmD_EYxF8WbafwwB59934FV7g21uMGQ@mail.gmail.com) Link: http://lkml.kernel.org/r/7232ef011d05a92f4caa86a5e9830d87966a2eaf.1470180926.git.joe@perches.comSigned-off-by:
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Joe Perches authored
Use get_maintainer to check the status of individual files. If "obsolete", suggest leaving the files alone. Link: http://lkml.kernel.org/r/7ceaa510dc9d2df05ec4b456baed7bb1415550b3.1471889575.git.joe@perches.comSigned-off-by:
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Noam Camus authored
Today there are platforms with many CPUs (up to 4K). Trying to boot only part of the CPUs may result in too long string. For example lets take NPS platform that is part of arch/arc. This platform have SMP system with 256 cores each with 16 HW threads (SMT machine) where HW thread appears as CPU to the kernel. In this example there is total of 4K CPUs. When one tries to boot only part of the HW threads from each core the string representing the map may be long... For example if for sake of performance we decided to boot only first half of HW threads of each core the map will look like: 0-7,16-23,32-39,...,4080-4087 This patch introduce new syntax to accommodate with such use case. I added an optional postfix to a range of CPUs which will choose according to given modulo the desired range of reminders i.e.: <cpus range>:sed_size/group_size For example, above map can be described in new syntax like this: 0-4095:8/16 Note that this patch is backward compatible with current syntax. [akpm@linux-foundation.org: rework documentation] Link: http://lkml.kernel.org/r/1473579629-4283-1-git-send-email-noamca@mellanox.comSigned-off-by:Noam Camus <noamca@mellanox.com> Cc: David Decotigny <decot@googlers.com> Cc: Ben Hutchings <ben@decadent.org.uk> Cc: David S. Miller <davem@davemloft.net> Cc: Pan Xinhui <xinhui@linux.vnet.ibm.com> Signed-off-by:
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