linux-kernel - [PATCH 01/32] cpumask: always use nr_cpu_ids in formatting and parsing functions

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Date:	Sat, 24 Jan 2015 09:03:07 -0500
From:	Tejun Heo <tj@...nel.org>
To:	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: [PATCH 01/32] cpumask: always use nr_cpu_ids in formatting and parsing functions

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 <tj@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Rusty Russell <rusty@...tcorp.com.au>
---
Hello,

Linus, this is the first of the three pre-requisite patches to convert
the users of the dedicated bitmap formatting functions over to
'%*pb[l]' formatting.

If this approach is agreed upon, I think it'd be best to route these
three patches through mainline soon so that subsystem conversion
patches can pull these in and apply per-subsystem conversion patches.

Thanks.

 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 b950e9d..98939d1 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);
 }
 
 /*
-- 
2.1.0

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