cpumask: make for_each_cpu_mask a bit smaller

The for_each_cpu_mask loop is used quite often in the kernel. It
makes use of two functions: first_cpu and next_cpu. This patch
changes for_each_cpu_mask to use only the latter. Because next_cpu
finds the next eligible cpu _after_ the given one, the iteration
variable has to be initialized to -1 and next_cpu has to be
called with this value before the first iteration. An x86_64
defconfig kernel (from sched/latest) is about 2500 bytes smaller
with this patch applied:

   text	   data	    bss	    dec	    hex	filename
6222517	 917952	 749932	7890401	 7865e1	vmlinux.orig
6219922	 917952	 749932	7887806	 785bbe	vmlinux

The same size reduction is seen for defconfig+MAXSMP

   text	   data	    bss	    dec	    hex	filename
6241772	2563968	1492716	10298456	 9d2458	vmlinux.orig
6239211	2563968	1492716	10295895	 9d1a57	vmlinux

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index b49472d1af840ce612d30083c6a751fe61f27bca..80226e776143242778708cfa682a2c0d58b38d3a 100644 (file)
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -370,10 +370,10 @@ int __any_online_cpu(const cpumask_t *mask);
 #define first_cpu(src)         __first_cpu(&(src))
 #define next_cpu(n, src)       __next_cpu((n), &(src))
 #define any_online_cpu(mask) __any_online_cpu(&(mask))
-#define for_each_cpu_mask(cpu, mask)           \
-       for ((cpu) = first_cpu(mask);           \
-               (cpu) < NR_CPUS;                \
-               (cpu) = next_cpu((cpu), (mask)))
+#define for_each_cpu_mask(cpu, mask)                   \
+       for ((cpu) = -1;                                \
+               (cpu) = next_cpu((cpu), (mask)),        \
+               (cpu) < NR_CPUS; )
 #endif
 
 #if NR_CPUS <= 64
@@ -387,10 +387,10 @@ int __any_online_cpu(const cpumask_t *mask);
 int __next_cpu_nr(int n, const cpumask_t *srcp);
 #define next_cpu_nr(n, src)    __next_cpu_nr((n), &(src))
 #define cpus_weight_nr(cpumask)        __cpus_weight(&(cpumask), nr_cpu_ids)
-#define for_each_cpu_mask_nr(cpu, mask)                \
-       for ((cpu) = first_cpu(mask);           \
-               (cpu) < nr_cpu_ids;             \
-               (cpu) = next_cpu_nr((cpu), (mask)))
+#define for_each_cpu_mask_nr(cpu, mask)                        \
+       for ((cpu) = -1;                                \
+               (cpu) = next_cpu_nr((cpu), (mask)),     \
+               (cpu) < nr_cpu_ids; )
 
 #endif /* NR_CPUS > 64 */