Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933226AbdI0FHE (ORCPT ); Wed, 27 Sep 2017 01:07:04 -0400 Received: from mail-pg0-f67.google.com ([74.125.83.67]:34671 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1033467AbdI0FGY (ORCPT ); Wed, 27 Sep 2017 01:06:24 -0400 X-Google-Smtp-Source: AOwi7QD0TYHiGBqpdSwXk3NJjKet2jEW07iHfab5MCpGz5AxYTyeWv/Ipm/mMJhdY55mwko/uye3vA== From: Gargi Sharma To: linux-kernel@vger.kernel.org Cc: riel@surriel.com, julia.lawall@lip6.fr, akpm@linux-foundation.org, mingo@kernel.org, pasha.tatashin@oracle.com, ktkhai@virtuozzo.com, oleg@redhat.com, Gargi Sharma Subject: [PATCH v2 2/2] pid: Remove pidhash Date: Wed, 27 Sep 2017 01:06:03 -0400 Message-Id: X-Mailer: git-send-email 2.7.4 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7965 Lines: 250 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. Signed-off-by: Gargi Sharma Reviewed-by: Rik van Riel --- include/linux/init_task.h | 1 - include/linux/pid.h | 2 -- include/linux/pid_namespace.h | 4 ++-- init/main.c | 1 - kernel/fork.c | 2 +- kernel/pid.c | 52 ++++++++----------------------------------- kernel/pid_namespace.c | 7 +++--- 7 files changed, 16 insertions(+), 53 deletions(-) diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 3c07ace..cc45798 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -104,7 +104,6 @@ extern struct group_info init_groups; .numbers = { { \ .nr = 0, \ .ns = &init_pid_ns, \ - .pid_chain = { .next = NULL, .pprev = NULL }, \ }, } \ } diff --git a/include/linux/pid.h b/include/linux/pid.h index 7195827..3915664 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -50,10 +50,8 @@ enum pid_type */ struct upid { - /* Try to keep pid_chain in the same cacheline as nr for find_vpid */ int nr; struct pid_namespace *ns; - struct hlist_node pid_chain; }; struct pid diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h index f4db4a7..7911b58 100644 --- a/include/linux/pid_namespace.h +++ b/include/linux/pid_namespace.h @@ -24,7 +24,7 @@ struct pid_namespace { struct kref kref; struct idr idr; struct rcu_head rcu; - unsigned int nr_hashed; + unsigned int pid_allocated; struct task_struct *child_reaper; struct kmem_cache *pid_cachep; unsigned int level; @@ -48,7 +48,7 @@ struct pid_namespace { extern struct pid_namespace init_pid_ns; -#define PIDNS_HASH_ADDING (1U << 31) +#define PIDNS_ADDING (1U << 31) #ifdef CONFIG_PID_NS static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns) diff --git a/init/main.c b/init/main.c index 9f4db20..c17a21b 100644 --- a/init/main.c +++ b/init/main.c @@ -562,7 +562,6 @@ asmlinkage __visible void __init start_kernel(void) * kmem_cache_init() */ setup_log_buf(0); - pidhash_init(); vfs_caches_init_early(); sort_main_extable(); trap_init(); diff --git a/kernel/fork.c b/kernel/fork.c index 1064618..c3518b8 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1853,7 +1853,7 @@ 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 207c49a..ae31f7d1 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -41,10 +41,6 @@ #include #include -#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; @@ -54,9 +50,6 @@ int pid_max = PID_MAX_DEFAULT; int pid_max_min = RESERVED_PIDS + 1; int pid_max_max = PID_MAX_LIMIT; -#define find_next_offset(map, off) \ - find_next_zero_bit((map)->page, BITS_PER_PAGE, off) - /* * PID-map pages start out as NULL, they get allocated upon * first use and are never deallocated. This way a low pid_max @@ -66,7 +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, @@ -125,8 +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 @@ -135,10 +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); @@ -208,12 +200,10 @@ 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)]); - upid->ns->nr_hashed++; + upid->ns->pid_allocated++; } spin_unlock_irq(&pidmap_lock); @@ -236,21 +226,13 @@ struct pid *alloc_pid(struct pid_namespace *ns) 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); @@ -432,26 +414,10 @@ 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) -{ - unsigned int pidhash_size; - - pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18, - HASH_EARLY | HASH_SMALL | HASH_ZERO, - &pidhash_shift, NULL, - 0, 4096); - pidhash_size = 1U << pidhash_shift; -} - 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 9af3625..dcfcd99 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -133,7 +133,8 @@ 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; @@ -259,7 +260,7 @@ 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(). @@ -273,7 +274,7 @@ 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(); } -- 2.7.4