/* * linux/lib/cmdline.c * Helper functions generally used for parsing kernel command line * and module options. * * Code and copyrights come from init/main.c and arch/i386/kernel/setup.c. * * This source code is licensed under the GNU General Public License, * Version 2. See the file COPYING for more details. * * GNU Indent formatting options for this file: -kr -i8 -npsl -pcs * */ #include #include #include /* * If a hyphen was found in get_option, this will handle the * range of numbers, M-N. This will expand the range and insert * the values[M, M+1, ..., N] into the ints array in get_options. */ static int get_range(char **str, int *pint) { int x, inc_counter, upper_range; (*str)++; upper_range = simple_strtol((*str), NULL, 0); inc_counter = upper_range - *pint; for (x = *pint; x < upper_range; x++) *pint++ = x; return inc_counter; } /** * get_option - Parse integer from an option string * @str: option string * @pint: (output) integer value parsed from @str * * Read an int from an option string; if available accept a subsequent * comma as well. * * Return values: * 0 - no int in string * 1 - int found, no subsequent comma * 2 - int found including a subsequent comma * 3 - hyphen found to denote a range */ int get_option(char **str, int *pint) { char *cur = *str; if (!cur || !(*cur)) return 0; *pint = simple_strtol(cur, str, 0); if (cur == *str) return 0; if (**str == ',') { (*str)++; return 2; } if (**str == '-') return 3; return 1; } EXPORT_SYMBOL(get_option); /** * get_options - Parse a string into a list of integers * @str: String to be parsed * @nints: size of integer array * @ints: integer array * * This function parses a string containing a comma-separated * list of integers, a hyphen-separated range of _positive_ integers, * or a combination of both. The parse halts when the array is * full, or when no more numbers can be retrieved from the * string. * * Return value is the character in the string which caused * the parse to end (typically a null terminator, if @str is * completely parseable). */ char *get_options(const char *str, int nints, int *ints) { int res, i = 1; while (i < nints) { res = get_option((char **)&str, ints + i); if (res == 0) break; if (res == 3) { int range_nums; range_nums = get_range((char **)&str, ints + i); if (range_nums < 0) break; /* * Decrement the result by one to leave out the * last number in the range. The next iteration * will handle the upper number in the range */ i += (range_nums - 1); } i++; if (res == 1) break; } ints[0] = i - 1; return (char *)str; } EXPORT_SYMBOL(get_options); /** * memparse - parse a string with mem suffixes into a number * @ptr: Where parse begins * @retptr: (output) Optional pointer to next char after parse completes * * Parses a string into a number. The number stored at @ptr is * potentially suffixed with K, M, G, T, P, E. */ unsigned long long memparse(const char *ptr, char **retptr) { char *endptr; /* local pointer to end of parsed string */ unsigned long long ret = simple_strtoull(ptr, &endptr, 0); switch (*endptr) { case 'E': case 'e': ret <<= 10; case 'P': case 'p': ret <<= 10; case 'T': case 't': ret <<= 10; case 'G': case 'g': ret <<= 10; case 'M': case 'm': ret <<= 10; case 'K': case 'k': ret <<= 10; endptr++; default: break; } if (retptr) *retptr = endptr; return ret; } EXPORT_SYMBOL(memparse); /** * parse_option_str - Parse a string and check an option is set or not * @str: String to be parsed * @option: option name * * This function parses a string containing a comma-separated list of * strings like a=b,c. * * Return true if there's such option in the string, or return false. */ bool parse_option_str(const char *str, const char *option) { while (*str) { if (!strncmp(str, option, strlen(option))) { str += strlen(option); if (!*str || *str == ',') return true; } while (*str && *str != ',') str++; if (*str == ',') str++; } return false; } lect>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 /net/mpls/mpls_iptunnel.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 'net/mpls/mpls_iptunnel.c')