***** BUILDING: This program's build procedure is fairly standard. Try: ./configure make make install Options to the configure script are up to you. For details, run: ./configure --help Please report build problems at: http://sourceforge.net/bugs/?func=addbug&group_id=4664 (yes, even non-Linux problems). ***** TIPS AND PROBLEMS: - Try to use flex as the lexical analyzer. The lex scanner is now separated from the flex version to allow the flex scanner to be optimized. It's also a lot harder to diagnose and debug problems without having full access to the particular platform and its version of lex being used. flex is available everywhere --- AT&T lex is not. - On Solaris, the native lex fails to catch our redefinition of YYLMAX early enough, which leads to possible buffer overflows. - On Linux systems (and possibly others) configure may fail if lex is a synomyn for flex. To fix, do the following: make distclean ./configure --with-flex make - On HP-UX several problems exist when using configure. Try the following to solve this: CFLAGS='-Ae -DYYCHAR_ARRAY' CURSES_LIBS=-lHcurses ./configure - On Tru64, formerly known as Digital Unix, formerly known as DEC OSF/1, the system-supplied libcurses causes cscope to terminate itself immediately as it comes back to foreground after being suspended by the user (Ctrl-Z). Using GNU Ncurses instead of OSF1 curses works around the problem. According to the lynx and ncurses people, this is a design problem of curses vs. signal handling, at the heart of it. - Solaris 2.8 on Intel hardware may not work using the vendor's curses implementation. Using the free NCurses should help. - Some ancient Unix filesytems supported only 14 characters in filenames. cscope no longer cares for that by default. If you want to run it on such a system, #define the macro SHORT_NAMES_ONLY manually (there's a definition in global.h you can uncomment). Browse to http://cscope.sourceforge.net for more current information, like reported bugs whose solutions haven't been put into this source distribution yet. gi/linux/net-next.git/log/fs/afs/misc.c'>
path: root/fs/afs/misc.c
os.c
diff options
AgeCommit message (Expand)AuthorFilesLines
context:
space:
mode:
authorDouglas Miller <dougmill@linux.vnet.ibm.com>2017-01-28 06:42:20 -0600
committerTejun Heo <tj@kernel.org>2017-01-28 07:49:42 -0500
commit966d2b04e070bc040319aaebfec09e0144dc3341 (patch)
tree4b96156e3d1dd4dfd6039b7c219c9dc4616da52d /drivers/usb/dwc3/dwc3-exynos.c
parent1b1bc42c1692e9b62756323c675a44cb1a1f9dbd (diff)
percpu-refcount: fix reference leak during percpu-atomic transition
percpu_ref_tryget() and percpu_ref_tryget_live() should return "true" IFF they acquire a reference. But the return value from atomic_long_inc_not_zero() is a long and may have high bits set, e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines is bool so the reference may actually be acquired but the routines return "false" which results in a reference leak since the caller assumes it does not need to do a corresponding percpu_ref_put(). This was seen when performing CPU hotplug during I/O, as hangs in blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start) raced with percpu_ref_tryget (blk_mq_timeout_work). Sample stack trace: __switch_to+0x2c0/0x450 __schedule+0x2f8/0x970 schedule+0x48/0xc0 blk_mq_freeze_queue_wait+0x94/0x120 blk_mq_queue_reinit_work+0xb8/0x180 blk_mq_queue_reinit_prepare+0x84/0xa0 cpuhp_invoke_callback+0x17c/0x600 cpuhp_up_callbacks+0x58/0x150 _cpu_up+0xf0/0x1c0 do_cpu_up+0x120/0x150 cpu_subsys_online+0x64/0xe0 device_online+0xb4/0x120 online_store+0xb4/0xc0 dev_attr_store+0x68/0xa0 sysfs_kf_write+0x80/0xb0 kernfs_fop_write+0x17c/0x250 __vfs_write+0x6c/0x1e0 vfs_write+0xd0/0x270 SyS_write+0x6c/0x110 system_call+0x38/0xe0 Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS, and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests. However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0 and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set. The fix is to make the tryget routines use an actual boolean internally instead of the atomic long result truncated to a int. Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751 Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com> Reviewed-by: Jens Axboe <axboe@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints") Cc: stable@vger.kernel.org # v3.18+
Diffstat (limited to 'drivers/usb/dwc3/dwc3-exynos.c')