diff options
author | Gargi Sharma <gs051095@gmail.com> | 2017-11-17 15:30:30 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-17 16:10:03 -0800 |
commit | 95846ecf9dac5089aed4b144d912225f8ef86ae4 (patch) | |
tree | 35da897650335522531d4d4ed37afd2fc26539ec /kernel/pid_namespace.c | |
parent | f9eb2fdd04d4e68fbea18970bbf65ace716d25b6 (diff) |
pid: replace pid bitmap implementation with IDR API
Patch series "Replacing PID bitmap implementation with IDR API", v4.
This series replaces kernel bitmap implementation of PID allocation with
IDR API. These patches are written to simplify the kernel by replacing
custom code with calls to generic code.
The following are the stats for pid and pid_namespace object files
before and after the replacement. There is a noteworthy change between
the IDR and bitmap implementation.
Before
text data bss dec hex filename
8447 3894 64 12405 3075 kernel/pid.o
After
text data bss dec hex filename
3397 304 0 3701 e75 kernel/pid.o
Before
text data bss dec hex filename
5692 1842 192 7726 1e2e kernel/pid_namespace.o
After
text data bss dec hex filename
2854 216 16 3086 c0e kernel/pid_namespace.o
The following are the stats for ps, pstree and calling readdir on /proc
for 10,000 processes.
ps:
With IDR API With bitmap
real 0m1.479s 0m2.319s
user 0m0.070s 0m0.060s
sys 0m0.289s 0m0.516s
pstree:
With IDR API With bitmap
real 0m1.024s 0m1.794s
user 0m0.348s 0m0.612s
sys 0m0.184s 0m0.264s
proc:
With IDR API With bitmap
real 0m0.059s 0m0.074s
user 0m0.000s 0m0.004s
sys 0m0.016s 0m0.016s
This patch (of 2):
Replace the current bitmap implementation for Process ID allocation.
Functions that are no longer required, for example, free_pidmap(),
alloc_pidmap(), etc. are removed. The rest of the functions are
modified to use the IDR API. The change was made to make the PID
allocation less complex by replacing custom code with calls to generic
API.
[gs051095@gmail.com: v6]
Link: http://lkml.kernel.org/r/1507760379-21662-2-git-send-email-gs051095@gmail.com
[avagin@openvz.org: restore the old behaviour of the ns_last_pid sysctl]
Link: http://lkml.kernel.org/r/20171106183144.16368-1-avagin@openvz.org
Link: http://lkml.kernel.org/r/1507583624-22146-2-git-send-email-gs051095@gmail.com
Signed-off-by: Gargi Sharma <gs051095@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
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: 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/pid_namespace.c')
-rw-r--r-- | kernel/pid_namespace.c | 53 |
1 files changed, 23 insertions, 30 deletions
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index 4918314893bc..ca7c8a8823b1 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -21,6 +21,7 @@ #include <linux/export.h> #include <linux/sched/task.h> #include <linux/sched/signal.h> +#include <linux/idr.h> struct pid_cache { int nr_ids; @@ -98,7 +99,6 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns struct pid_namespace *ns; unsigned int level = parent_pid_ns->level + 1; struct ucounts *ucounts; - int i; int err; err = -EINVAL; @@ -117,17 +117,15 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns if (ns == NULL) goto out_dec; - ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); - if (!ns->pidmap[0].page) - goto out_free; + idr_init(&ns->idr); ns->pid_cachep = create_pid_cachep(level + 1); if (ns->pid_cachep == NULL) - goto out_free_map; + goto out_free_idr; err = ns_alloc_inum(&ns->ns); if (err) - goto out_free_map; + goto out_free_idr; ns->ns.ops = &pidns_operations; kref_init(&ns->kref); @@ -138,17 +136,10 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns ns->nr_hashed = PIDNS_HASH_ADDING; INIT_WORK(&ns->proc_work, proc_cleanup_work); - set_bit(0, ns->pidmap[0].page); - atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1); - - for (i = 1; i < PIDMAP_ENTRIES; i++) - atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE); - return ns; -out_free_map: - kfree(ns->pidmap[0].page); -out_free: +out_free_idr: + idr_destroy(&ns->idr); kmem_cache_free(pid_ns_cachep, ns); out_dec: dec_pid_namespaces(ucounts); @@ -168,11 +159,9 @@ static void delayed_free_pidns(struct rcu_head *p) static void destroy_pid_namespace(struct pid_namespace *ns) { - int i; - ns_free_inum(&ns->ns); - for (i = 0; i < PIDMAP_ENTRIES; i++) - kfree(ns->pidmap[i].page); + + idr_destroy(&ns->idr); call_rcu(&ns->rcu, delayed_free_pidns); } @@ -213,6 +202,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) int rc; struct task_struct *task, *me = current; int init_pids = thread_group_leader(me) ? 1 : 2; + struct pid *pid; /* Don't allow any more processes into the pid namespace */ disable_pid_allocation(pid_ns); @@ -239,20 +229,16 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) * maintain a tasklist for each pid namespace. * */ + rcu_read_lock(); read_lock(&tasklist_lock); - nr = next_pidmap(pid_ns, 1); - while (nr > 0) { - rcu_read_lock(); - - task = pid_task(find_vpid(nr), PIDTYPE_PID); + nr = 2; + idr_for_each_entry_continue(&pid_ns->idr, pid, nr) { + task = pid_task(pid, PIDTYPE_PID); if (task && !__fatal_signal_pending(task)) send_sig_info(SIGKILL, SEND_SIG_FORCED, task); - - rcu_read_unlock(); - - nr = next_pidmap(pid_ns, nr); } read_unlock(&tasklist_lock); + rcu_read_unlock(); /* * Reap the EXIT_ZOMBIE children we had before we ignored SIGCHLD. @@ -301,6 +287,7 @@ static int pid_ns_ctl_handler(struct ctl_table *table, int write, { struct pid_namespace *pid_ns = task_active_pid_ns(current); struct ctl_table tmp = *table; + int ret, next; if (write && !ns_capable(pid_ns->user_ns, CAP_SYS_ADMIN)) return -EPERM; @@ -311,8 +298,14 @@ static int pid_ns_ctl_handler(struct ctl_table *table, int write, * it should synchronize its usage with external means. */ - tmp.data = &pid_ns->last_pid; - return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); + next = idr_get_cursor(&pid_ns->idr) - 1; + + tmp.data = &next; + ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); + if (!ret && write) + idr_set_cursor(&pid_ns->idr, next + 1); + + return ret; } extern int pid_max; |