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authorGargi Sharma <gs051095@gmail.com>2017-11-17 15:30:34 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-17 16:10:04 -0800
commite8cfbc245e24887e3c30235f71e9e9405e0cfc39 (patch)
tree0a9bc847f3c3328e822d1b9f0790999282390cf3 /kernel
parent95846ecf9dac5089aed4b144d912225f8ef86ae4 (diff)
pid: remove pidhash
pidhash is no longer required as all the information can be looked up from idr tree. nr_hashed represented the number of pids that had been hashed. Since, nr_hashed and PIDNS_HASH_ADDING are no longer relevant, it has been renamed to pid_allocated and PIDNS_ADDING respectively. [gs051095@gmail.com: v6] Link: http://lkml.kernel.org/r/1507760379-21662-3-git-send-email-gs051095@gmail.com Link: http://lkml.kernel.org/r/1507583624-22146-3-git-send-email-gs051095@gmail.com Signed-off-by: Gargi Sharma <gs051095@gmail.com> Reviewed-by: Rik van Riel <riel@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> [ia64] Cc: Julia Lawall <julia.lawall@lip6.fr> Cc: Ingo Molnar <mingo@kernel.org> Cc: Pavel Tatashin <pasha.tatashin@oracle.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/fork.c2
-rw-r--r--kernel/pid.c48
-rw-r--r--kernel/pid_namespace.c6
3 files changed, 14 insertions, 42 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 4e55eedba8d6..432eadf6b58c 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1871,7 +1871,7 @@ static __latent_entropy struct task_struct *copy_process(
retval = -ERESTARTNOINTR;
goto bad_fork_cancel_cgroup;
}
- if (unlikely(!(ns_of_pid(pid)->nr_hashed & PIDNS_HASH_ADDING))) {
+ if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
retval = -ENOMEM;
goto bad_fork_cancel_cgroup;
}
diff --git a/kernel/pid.c b/kernel/pid.c
index 0ce59369632f..b13b624e2c49 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -41,10 +41,6 @@
#include <linux/sched/task.h>
#include <linux/idr.h>
-#define pid_hashfn(nr, ns) \
- hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
-static struct hlist_head *pid_hash;
-static unsigned int pidhash_shift = 4;
struct pid init_struct_pid = INIT_STRUCT_PID;
int pid_max = PID_MAX_DEFAULT;
@@ -54,7 +50,6 @@ int pid_max = PID_MAX_DEFAULT;
int pid_max_min = RESERVED_PIDS + 1;
int pid_max_max = PID_MAX_LIMIT;
-
/*
* PID-map pages start out as NULL, they get allocated upon
* first use and are never deallocated. This way a low pid_max
@@ -64,7 +59,7 @@ int pid_max_max = PID_MAX_LIMIT;
struct pid_namespace init_pid_ns = {
.kref = KREF_INIT(2),
.idr = IDR_INIT,
- .nr_hashed = PIDNS_HASH_ADDING,
+ .pid_allocated = PIDNS_ADDING,
.level = 0,
.child_reaper = &init_task,
.user_ns = &init_user_ns,
@@ -123,8 +118,7 @@ void free_pid(struct pid *pid)
for (i = 0; i <= pid->level; i++) {
struct upid *upid = pid->numbers + i;
struct pid_namespace *ns = upid->ns;
- hlist_del_rcu(&upid->pid_chain);
- switch (--ns->nr_hashed) {
+ switch (--ns->pid_allocated) {
case 2:
case 1:
/* When all that is left in the pid namespace
@@ -133,10 +127,10 @@ void free_pid(struct pid *pid)
*/
wake_up_process(ns->child_reaper);
break;
- case PIDNS_HASH_ADDING:
+ case PIDNS_ADDING:
/* Handle a fork failure of the first process */
WARN_ON(ns->child_reaper);
- ns->nr_hashed = 0;
+ ns->pid_allocated = 0;
/* fall through */
case 0:
schedule_work(&ns->proc_work);
@@ -212,14 +206,12 @@ struct pid *alloc_pid(struct pid_namespace *ns)
upid = pid->numbers + ns->level;
spin_lock_irq(&pidmap_lock);
- if (!(ns->nr_hashed & PIDNS_HASH_ADDING))
+ if (!(ns->pid_allocated & PIDNS_ADDING))
goto out_unlock;
for ( ; upid >= pid->numbers; --upid) {
- hlist_add_head_rcu(&upid->pid_chain,
- &pid_hash[pid_hashfn(upid->nr, upid->ns)]);
/* Make the PID visible to find_pid_ns. */
idr_replace(&upid->ns->idr, pid, upid->nr);
- upid->ns->nr_hashed++;
+ upid->ns->pid_allocated++;
}
spin_unlock_irq(&pidmap_lock);
@@ -243,21 +235,13 @@ out_free:
void disable_pid_allocation(struct pid_namespace *ns)
{
spin_lock_irq(&pidmap_lock);
- ns->nr_hashed &= ~PIDNS_HASH_ADDING;
+ ns->pid_allocated &= ~PIDNS_ADDING;
spin_unlock_irq(&pidmap_lock);
}
struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
{
- struct upid *pnr;
-
- hlist_for_each_entry_rcu(pnr,
- &pid_hash[pid_hashfn(nr, ns)], pid_chain)
- if (pnr->nr == nr && pnr->ns == ns)
- return container_of(pnr, struct pid,
- numbers[ns->level]);
-
- return NULL;
+ return idr_find(&ns->idr, nr);
}
EXPORT_SYMBOL_GPL(find_pid_ns);
@@ -413,6 +397,7 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
if (type != PIDTYPE_PID) {
if (type == __PIDTYPE_TGID)
type = PIDTYPE_PID;
+
task = task->group_leader;
}
nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns);
@@ -439,23 +424,10 @@ struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
return idr_get_next(&ns->idr, &nr);
}
-/*
- * The pid hash table is scaled according to the amount of memory in the
- * machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or
- * more.
- */
-void __init pidhash_init(void)
-{
- pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18,
- HASH_EARLY | HASH_SMALL | HASH_ZERO,
- &pidhash_shift, NULL,
- 0, 4096);
-}
-
void __init pid_idr_init(void)
{
/* Verify no one has done anything silly: */
- BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_HASH_ADDING);
+ BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_ADDING);
/* bump default and minimum pid_max based on number of cpus */
pid_max = min(pid_max_max, max_t(int, pid_max,
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index ca7c8a8823b1..0b53eef7d34b 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -133,7 +133,7 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
ns->parent = get_pid_ns(parent_pid_ns);
ns->user_ns = get_user_ns(user_ns);
ns->ucounts = ucounts;
- ns->nr_hashed = PIDNS_HASH_ADDING;
+ ns->pid_allocated = PIDNS_ADDING;
INIT_WORK(&ns->proc_work, proc_cleanup_work);
return ns;
@@ -254,7 +254,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
* sys_wait4() above can't reap the EXIT_DEAD children but we do not
* really care, we could reparent them to the global init. We could
* exit and reap ->child_reaper even if it is not the last thread in
- * this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(),
+ * this pid_ns, free_pid(pid_allocated == 0) calls proc_cleanup_work(),
* pid_ns can not go away until proc_kill_sb() drops the reference.
*
* But this ns can also have other tasks injected by setns()+fork().
@@ -268,7 +268,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
*/
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
- if (pid_ns->nr_hashed == init_pids)
+ if (pid_ns->pid_allocated == init_pids)
break;
schedule();
}

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