projects/linux·commit c417f024

[PATCH] cpuset: remove test for null cpuset from alloc code path

c417f024 · Paul Jackson <[email protected]> · 2006-01-08 01:02:01 -08:00

Remove a couple of more lines of code from the cpuset hooks in the page
allocation code path.

There was a check for a NULL cpuset pointer in the routine
cpuset_update_task_memory_state() that was only needed during system boot,
after the memory subsystem was initialized, before the cpuset subsystem was
initialized, to catch a NULL task->cpuset pointer.

Add a cpuset_init_early() routine, just before the mem_init() call in
init/main.c, that sets up just enough of the init tasks cpuset structure to
render cpuset_update_task_memory_state() calls harmless.

Signed-off-by: Paul Jackson <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Commit
c417f0242ebe578924a30d4e53d35b5059fed4e7
Parents
04c19fa6

Changes

3 files changed · +19 −6

FileStatusAddDelContent
include/linux/cpuset.hmodified+2−0View file
init/main.cmodified+1−0View file
kernel/cpuset.cmodified+16−6View file

include/linux/cpuset.h

View file
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index 34081c1..c472f97 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -16,6 +16,7 @@
extern int number_of_cpusets; /* How many cpusets are defined in system? */
+extern int cpuset_init_early(void);
extern int cpuset_init(void);
extern void cpuset_init_smp(void);
extern void cpuset_fork(struct task_struct *p);
@@ -49,6 +50,7 @@ extern char *cpuset_task_status_allowed(struct task_struct *task, char *buffer);
#else /* !CONFIG_CPUSETS */
+static inline int cpuset_init_early(void) { return 0; }
static inline int cpuset_init(void) { return 0; }
static inline void cpuset_init_smp(void) {}
static inline void cpuset_fork(struct task_struct *p) {}

init/main.c

View file
diff --git a/init/main.c b/init/main.c
index 2ed3638..afe5eb8 100644
--- a/init/main.c
+++ b/init/main.c
@@ -512,6 +512,7 @@ asmlinkage void __init start_kernel(void)
}
#endif
vfs_caches_init_early();
+ cpuset_init_early();
mem_init();
kmem_cache_init();
setup_per_cpu_pageset();

kernel/cpuset.c

View file
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index cf8203a..fc949e4 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -603,9 +603,7 @@ static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask)
* Do not call this routine if in_interrupt().
*
* Call without callback_sem or task_lock() held. May be called
- * with or without manage_sem held. Except in early boot or
- * an exiting task, when tsk->cpuset is NULL, this routine will
- * acquire task_lock(). We don't need to use task_lock to guard
+ * with or without manage_sem held. Doesn't need task_lock to guard
* against another task changing a non-NULL cpuset pointer to NULL,
* as that is only done by a task on itself, and if the current task
* is here, it is not simultaneously in the exit code NULL'ing its
@@ -631,9 +629,6 @@ void cpuset_update_task_memory_state()
struct task_struct *tsk = current;
struct cpuset *cs = tsk->cpuset;
- if (unlikely(!cs))
- return;
-
task_lock(tsk);
my_cpusets_mem_gen = cs->mems_generation;
task_unlock(tsk);
@@ -1836,6 +1831,21 @@ static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry)
return 0;
}
+/*
+ * cpuset_init_early - just enough so that the calls to
+ * cpuset_update_task_memory_state() in early init code
+ * are harmless.
+ */
+
+int __init cpuset_init_early(void)
+{
+ struct task_struct *tsk = current;
+
+ tsk->cpuset = &top_cpuset;
+ tsk->cpuset->mems_generation = atomic_read(&cpuset_mems_generation);
+ return 0;
+}
+
/**
* cpuset_init - initialize cpusets at system boot
*