From 8db049b3d666b3676ff4a976e03c14de302bf9fa Mon Sep 17 00:00:00 2001 From: "Raphael S. Carvalho" Date: Tue, 30 Apr 2013 15:28:26 -0700 Subject: kernel/pid.c: improve flow of a loop inside alloc_pidmap. find_next_offset() searches for an available "cleaned bit" in the respective pid bitmap (page), so returns the offset if found, otherwise it returns a value equals to BITS_PER_PAGE. For example, suppose find_next_offset didn't find any available bit, so there's no purpose to call mk_pid (Wasteful Cpu Cycles). Therefore, I found it could be better to call mk_pid after the checking (offset < BITS_PER_PAGE) returned sucessfully! Another point: If (offset < BITS_PER_PAGE) results in a "failure", then mk_pid would be called again afterwards. [akpm@linux-foundation.org: simplify code] Signed-off-by: Raphael S. Carvalho Cc: "Eric W. Biederman" Cc: Serge Hallyn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/pid.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'kernel/pid.c') diff --git a/kernel/pid.c b/kernel/pid.c index 047dc6264638..8147bdf22f36 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -183,15 +183,19 @@ static int alloc_pidmap(struct pid_namespace *pid_ns) break; } if (likely(atomic_read(&map->nr_free))) { - do { + for ( ; ; ) { if (!test_and_set_bit(offset, map->page)) { atomic_dec(&map->nr_free); set_last_pid(pid_ns, last, pid); return pid; } offset = find_next_offset(map, offset); + if (offset >= BITS_PER_PAGE) + break; pid = mk_pid(pid_ns, map, offset); - } while (offset < BITS_PER_PAGE && pid < pid_max); + if (pid >= pid_max) + break; + } } if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) { ++map; -- cgit v1.2.3 From 5cc5445164c16d32bab2912fac28356ab07aa8b4 Mon Sep 17 00:00:00 2001 From: "Raphael S.Carvalho" Date: Tue, 30 Apr 2013 15:28:27 -0700 Subject: pid_namespace.c/.h: simplify defines Move BITS_PER_PAGE from pid_namespace.c to pid_namespace.h, since we can simplify the define PID_MAP_ENTRIES by using the BITS_PER_PAGE. [akpm@linux-foundation.org: kernel/pid.c:54:1: warning: "BITS_PER_PAGE" redefined] Signed-off-by: Raphael S.Carvalho Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/pid.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'kernel/pid.c') diff --git a/kernel/pid.c b/kernel/pid.c index 8147bdf22f36..6283d6412aff 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -51,9 +51,6 @@ int pid_max = PID_MAX_DEFAULT; int pid_max_min = RESERVED_PIDS + 1; int pid_max_max = PID_MAX_LIMIT; -#define BITS_PER_PAGE (PAGE_SIZE*8) -#define BITS_PER_PAGE_MASK (BITS_PER_PAGE-1) - static inline int mk_pid(struct pid_namespace *pid_ns, struct pidmap *map, int off) { -- cgit v1.2.3 From 0bb80f240520c4148b623161e7856858c021696d Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 12 Apr 2013 01:50:06 +0100 Subject: proc: Split the namespace stuff out into linux/proc_ns.h Split the proc namespace stuff out into linux/proc_ns.h. Signed-off-by: David Howells cc: netdev@vger.kernel.org cc: Serge E. Hallyn cc: Eric W. Biederman Signed-off-by: Al Viro --- kernel/pid.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/pid.c') diff --git a/kernel/pid.c b/kernel/pid.c index 047dc6264638..686255e2c39e 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -36,6 +36,7 @@ #include #include #include +#include #include #define pid_hashfn(nr, ns) \ -- cgit v1.2.3