From: Mike Rapoport Date: Tue, 6 Feb 2018 23:40:17 +0000 (-0800) Subject: pids: introduce find_get_task_by_vpid() helper X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=2ee0826085d1c0281cb60c1f4bc3e0c27efeedc3;p=openwrt%2Fstaging%2Fblogic.git pids: introduce find_get_task_by_vpid() helper There are several functions that do find_task_by_vpid() followed by get_task_struct(). We can use a helper function instead. Link: http://lkml.kernel.org/r/1509602027-11337-1-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport Acked-by: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c index c44f002e8f6b..858602494096 100644 --- a/arch/ia64/kernel/perfmon.c +++ b/arch/ia64/kernel/perfmon.c @@ -2610,17 +2610,10 @@ pfm_get_task(pfm_context_t *ctx, pid_t pid, struct task_struct **task) if (pid < 2) return -EPERM; if (pid != task_pid_vnr(current)) { - - read_lock(&tasklist_lock); - - p = find_task_by_vpid(pid); - /* make sure task cannot go away while we operate on it */ - if (p) get_task_struct(p); - - read_unlock(&tasklist_lock); - - if (p == NULL) return -ESRCH; + p = find_get_task_by_vpid(pid); + if (!p) + return -ESRCH; } ret = pfm_task_incompatible(ctx, p); diff --git a/include/linux/sched.h b/include/linux/sched.h index 166144c04ef6..ce5a27304b03 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1489,6 +1489,11 @@ static inline struct thread_info *task_thread_info(struct task_struct *task) extern struct task_struct *find_task_by_vpid(pid_t nr); extern struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *ns); +/* + * find a task by its virtual pid and get the task struct + */ +extern struct task_struct *find_get_task_by_vpid(pid_t nr); + extern int wake_up_state(struct task_struct *tsk, unsigned int state); extern int wake_up_process(struct task_struct *tsk); extern void wake_up_new_task(struct task_struct *tsk); diff --git a/kernel/futex.c b/kernel/futex.c index 7f719d110908..1f450e092c74 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -862,24 +862,6 @@ static void put_pi_state(struct futex_pi_state *pi_state) } } -/* - * Look up the task based on what TID userspace gave us. - * We dont trust it. - */ -static struct task_struct *futex_find_get_task(pid_t pid) -{ - struct task_struct *p; - - rcu_read_lock(); - p = find_task_by_vpid(pid); - if (p) - get_task_struct(p); - - rcu_read_unlock(); - - return p; -} - #ifdef CONFIG_FUTEX_PI /* @@ -1183,7 +1165,7 @@ static int attach_to_pi_owner(u32 uval, union futex_key *key, */ if (!pid) return -ESRCH; - p = futex_find_get_task(pid); + p = find_get_task_by_vpid(pid); if (!p) return -ESRCH; diff --git a/kernel/pid.c b/kernel/pid.c index 5d30c87e3c42..ed6c343fe50d 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -343,6 +343,19 @@ struct task_struct *find_task_by_vpid(pid_t vnr) return find_task_by_pid_ns(vnr, task_active_pid_ns(current)); } +struct task_struct *find_get_task_by_vpid(pid_t nr) +{ + struct task_struct *task; + + rcu_read_lock(); + task = find_task_by_vpid(nr); + if (task) + get_task_struct(task); + rcu_read_unlock(); + + return task; +} + struct pid *get_task_pid(struct task_struct *task, enum pid_type type) { struct pid *pid; diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 5e1d713c8e61..21fec73d45d4 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -1103,21 +1103,6 @@ int ptrace_request(struct task_struct *child, long request, return ret; } -static struct task_struct *ptrace_get_task_struct(pid_t pid) -{ - struct task_struct *child; - - rcu_read_lock(); - child = find_task_by_vpid(pid); - if (child) - get_task_struct(child); - rcu_read_unlock(); - - if (!child) - return ERR_PTR(-ESRCH); - return child; -} - #ifndef arch_ptrace_attach #define arch_ptrace_attach(child) do { } while (0) #endif @@ -1135,9 +1120,9 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr, goto out; } - child = ptrace_get_task_struct(pid); - if (IS_ERR(child)) { - ret = PTR_ERR(child); + child = find_get_task_by_vpid(pid); + if (!child) { + ret = -ESRCH; goto out; } @@ -1281,9 +1266,9 @@ COMPAT_SYSCALL_DEFINE4(ptrace, compat_long_t, request, compat_long_t, pid, goto out; } - child = ptrace_get_task_struct(pid); - if (IS_ERR(child)) { - ret = PTR_ERR(child); + child = find_get_task_by_vpid(pid); + if (!child) { + ret = -ESRCH; goto out; } diff --git a/kernel/taskstats.c b/kernel/taskstats.c index 4559e914452b..4e62a4a8fa91 100644 --- a/kernel/taskstats.c +++ b/kernel/taskstats.c @@ -194,11 +194,7 @@ static int fill_stats_for_pid(pid_t pid, struct taskstats *stats) { struct task_struct *tsk; - rcu_read_lock(); - tsk = find_task_by_vpid(pid); - if (tsk) - get_task_struct(tsk); - rcu_read_unlock(); + tsk = find_get_task_by_vpid(pid); if (!tsk) return -ESRCH; fill_stats(current_user_ns(), task_active_pid_ns(current), tsk, stats); diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c index 8973cd231ece..16424b9ae424 100644 --- a/mm/process_vm_access.c +++ b/mm/process_vm_access.c @@ -197,11 +197,7 @@ static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter, } /* Get process information */ - rcu_read_lock(); - task = find_task_by_vpid(pid); - if (task) - get_task_struct(task); - rcu_read_unlock(); + task = find_get_task_by_vpid(pid); if (!task) { rc = -ESRCH; goto free_proc_pages; diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c index 8298e094f4f7..ffda91a4a1aa 100644 --- a/security/yama/yama_lsm.c +++ b/security/yama/yama_lsm.c @@ -250,15 +250,10 @@ int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3, } else { struct task_struct *tracer; - rcu_read_lock(); - tracer = find_task_by_vpid(arg2); - if (tracer) - get_task_struct(tracer); - else + tracer = find_get_task_by_vpid(arg2); + if (!tracer) { rc = -EINVAL; - rcu_read_unlock(); - - if (tracer) { + } else { rc = yama_ptracer_add(tracer, myself); put_task_struct(tracer); }