From 513e3d2d11c9f05db1edc70deb18a82555cf9309 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 13 Feb 2015 14:36:50 -0800 Subject: [PATCH] cpumask: always use nr_cpu_ids in formatting and parsing functions bitmap implements two variants of scnprintf functions to format a bitmap into a string and cpumask and nodemask wrap them to provide equivalent interfaces. The scnprintf family of functions require a string buffer as an output target which complicates code paths which just want to print out the mask through printk for informational or debug purposes as they have to worry about how large the buffer should be and whether it's too large to allocate on stack. Neither cpumask or nodemask provides a guildeline on how large the target buffer should be forcing users come up with their own solutions - some allocate an arbitrarily sized buffer which is small enough to allocate on stack but may be too short in corner cases, other come up with a custom upper limit calculation considering the output format, some allocate the buffer dynamically while one resorted to using lock to synchronize access to a static buffer. This is an artificial problem which is being solved repeatedly for no benefit. In a lot of cases, the output area already exists and can be targeted directly making the intermediate buffer unnecessary. This patchset teaches printf family of functions how to format bitmaps and replace the dedicated formatting functions with it. Pointer formatting is extended to cover bitmap formatting. It uses the field width for the number of bits instead of precision. The format used is '%*pb[l]', with the optional trailing 'l' specifying list format instead of hex masks. For more details, please see 0002. This patch (of 31): Currently, the formatting and parsing functions in cpumask.h use nr_cpumask_bits like other cpumask functions; however, nr_cpumask_bits is either NR_CPUS or nr_cpu_ids depending on CONFIG_CPUMASK_OFFSTACK. This leads to inconsistent behaviors. With CONFIG_NR_CPUS=512 and !CONFIG_CPUMASK_OFFSTACK # cat /sys/devices/virtual/net/lo/queues/rx-0/rps_cpus 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000 # cat /proc/self/status | grep Cpus_allowed: Cpus_allowed: f With CONFIG_NR_CPUS=1024 and CONFIG_CPUMASK_OFFSTACK (fedora default) # cat /sys/devices/virtual/net/lo/queues/rx-0/rps_cpus 0 # cat /proc/self/status | grep Cpus_allowed: Cpus_allowed: f Note that /proc/self/status is always using nr_cpu_ids regardless of config. This is because seq cpumask formattings functions always use nr_cpu_ids. Given that the same output fields may switch between the two forms, converging on nr_cpu_ids always isn't too likely to surprise userland. This patch updates the formatting and parsing functions in cpumask.h to always use nr_cpu_ids. There's no point in dealing with CPUs which aren't even possible on the machine. Signed-off-by: Tejun Heo Cc: "David S. Miller" Cc: "James E.J. Bottomley" Cc: "John W. Linville" Cc: "Paul E. McKenney" Cc: Benjamin Herrenschmidt Cc: Chris Metcalf Cc: Chris Zankel Cc: Christoph Lameter Cc: Dmitry Torokhov Cc: Fenghua Yu Cc: Greg Kroah-Hartman Cc: Ingo Molnar Cc: Li Zefan Cc: Max Filippov Cc: Mike Travis Cc: Pekka Enberg Cc: Peter Zijlstra Cc: Russell King Acked-by: Rusty Russell Cc: Steffen Klassert Cc: Steven Rostedt Cc: Thomas Gleixner Cc: Tony Luck Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/cpumask.h | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index ff9044286d88..ee9acb0ce542 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -550,7 +550,7 @@ static inline void cpumask_copy(struct cpumask *dstp, static inline int cpumask_scnprintf(char *buf, int len, const struct cpumask *srcp) { - return bitmap_scnprintf(buf, len, cpumask_bits(srcp), nr_cpumask_bits); + return bitmap_scnprintf(buf, len, cpumask_bits(srcp), nr_cpu_ids); } /** @@ -564,7 +564,7 @@ static inline int cpumask_scnprintf(char *buf, int len, static inline int cpumask_parse_user(const char __user *buf, int len, struct cpumask *dstp) { - return bitmap_parse_user(buf, len, cpumask_bits(dstp), nr_cpumask_bits); + return bitmap_parse_user(buf, len, cpumask_bits(dstp), nr_cpu_ids); } /** @@ -579,7 +579,7 @@ static inline int cpumask_parselist_user(const char __user *buf, int len, struct cpumask *dstp) { return bitmap_parselist_user(buf, len, cpumask_bits(dstp), - nr_cpumask_bits); + nr_cpu_ids); } /** @@ -595,7 +595,7 @@ static inline int cpulist_scnprintf(char *buf, int len, const struct cpumask *srcp) { return bitmap_scnlistprintf(buf, len, cpumask_bits(srcp), - nr_cpumask_bits); + nr_cpu_ids); } /** @@ -610,7 +610,7 @@ static inline int cpumask_parse(const char *buf, struct cpumask *dstp) char *nl = strchr(buf, '\n'); unsigned int len = nl ? (unsigned int)(nl - buf) : strlen(buf); - return bitmap_parse(buf, len, cpumask_bits(dstp), nr_cpumask_bits); + return bitmap_parse(buf, len, cpumask_bits(dstp), nr_cpu_ids); } /** @@ -622,7 +622,7 @@ static inline int cpumask_parse(const char *buf, struct cpumask *dstp) */ static inline int cpulist_parse(const char *buf, struct cpumask *dstp) { - return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpumask_bits); + return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpu_ids); } /** @@ -817,7 +817,7 @@ static inline ssize_t cpumap_print_to_pagebuf(bool list, char *buf, const struct cpumask *mask) { return bitmap_print_to_pagebuf(list, buf, cpumask_bits(mask), - nr_cpumask_bits); + nr_cpu_ids); } /* -- 2.30.2