From 4af1036df4dd4f0d59fad9d82ed456bfa2e73fa6 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 10 Dec 2014 15:45:10 -0800 Subject: proc: task_state: read cred->group_info outside of task_lock() task_state() reads cred->group_info under task_lock() because a long ago it was task_struct->group_info and it was actually protected by task->alloc_lock. Today this task_unlock() after rcu_read_unlock() just adds the confusion, move task_unlock() up. Signed-off-by: Oleg Nesterov Cc: Aaron Tomlin Cc: Alexey Dobriyan Cc: "Eric W. Biederman" , Cc: Sterling Alexander Cc: Peter Zijlstra Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/array.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'fs/proc/array.c') diff --git a/fs/proc/array.c b/fs/proc/array.c index cd3653e4f35c..b5810c228c10 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -201,11 +201,10 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, "FDSize:\t%d\n" "Groups:\t", fdt ? fdt->max_fds : 0); + task_unlock(p); rcu_read_unlock(); group_info = cred->group_info; - task_unlock(p); - for (g = 0; g < group_info->ngroups; g++) seq_printf(m, "%d ", from_kgid_munged(user_ns, GROUP_AT(group_info, g))); -- cgit v1.2.3 From 0f4a0d53f20c76a70cb5b69b6aa237de2107e171 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 10 Dec 2014 15:45:12 -0800 Subject: proc: task_state: deuglify the max_fds calculation 1. The usage of fdt looks very ugly, it can't be NULL if ->files is not NULL. We can use "unsigned int max_fds" instead. 2. This also allows to move seq_printf(max_fds) outside of task_lock() and join it with the previous seq_printf(). See also the next patch. Signed-off-by: Oleg Nesterov Cc: Aaron Tomlin Cc: Alexey Dobriyan Cc: "Eric W. Biederman" , Cc: Sterling Alexander Cc: Peter Zijlstra Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/array.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) (limited to 'fs/proc/array.c') diff --git a/fs/proc/array.c b/fs/proc/array.c index b5810c228c10..7c8d9aecb070 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -157,9 +157,9 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, struct user_namespace *user_ns = seq_user_ns(m); struct group_info *group_info; int g; - struct fdtable *fdt = NULL; const struct cred *cred; pid_t ppid, tpid; + unsigned int max_fds = 0; rcu_read_lock(); ppid = pid_alive(p) ? @@ -171,6 +171,12 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, tpid = task_pid_nr_ns(tracer, ns); } cred = get_task_cred(p); + + task_lock(p); + if (p->files) + max_fds = files_fdtable(p->files)->max_fds; + task_unlock(p); + seq_printf(m, "State:\t%s\n" "Tgid:\t%d\n" @@ -179,7 +185,8 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, "PPid:\t%d\n" "TracerPid:\t%d\n" "Uid:\t%d\t%d\t%d\t%d\n" - "Gid:\t%d\t%d\t%d\t%d\n", + "Gid:\t%d\t%d\t%d\t%d\n" + "FDSize:\t%d\nGroups:\t", get_task_state(p), task_tgid_nr_ns(p, ns), task_numa_group_id(p), @@ -192,16 +199,8 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, from_kgid_munged(user_ns, cred->gid), from_kgid_munged(user_ns, cred->egid), from_kgid_munged(user_ns, cred->sgid), - from_kgid_munged(user_ns, cred->fsgid)); - - task_lock(p); - if (p->files) - fdt = files_fdtable(p->files); - seq_printf(m, - "FDSize:\t%d\n" - "Groups:\t", - fdt ? fdt->max_fds : 0); - task_unlock(p); + from_kgid_munged(user_ns, cred->fsgid), + max_fds); rcu_read_unlock(); group_info = cred->group_info; -- cgit v1.2.3 From b0fafc11115938a3215723f37e8e9cc6a94b05b0 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 10 Dec 2014 15:45:15 -0800 Subject: proc: task_state: move the main seq_printf() outside of rcu_read_lock() task_state() does seq_printf() under rcu_read_lock(), but this is only needed for task_tgid_nr_ns() and task_numa_group_id(). We can calculate tgid/ngid and drop rcu lock. Signed-off-by: Oleg Nesterov Cc: Aaron Tomlin Cc: Alexey Dobriyan Cc: "Eric W. Biederman" , Cc: Sterling Alexander Cc: Peter Zijlstra Cc: Roland McGrath Reviewed-by: Paul E. McKenney Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/array.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'fs/proc/array.c') diff --git a/fs/proc/array.c b/fs/proc/array.c index 7c8d9aecb070..800e30f8f284 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -158,7 +158,7 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, struct group_info *group_info; int g; const struct cred *cred; - pid_t ppid, tpid; + pid_t ppid, tpid, tgid, ngid; unsigned int max_fds = 0; rcu_read_lock(); @@ -170,12 +170,16 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, if (tracer) tpid = task_pid_nr_ns(tracer, ns); } + + tgid = task_tgid_nr_ns(p, ns); + ngid = task_numa_group_id(p); cred = get_task_cred(p); task_lock(p); if (p->files) max_fds = files_fdtable(p->files)->max_fds; task_unlock(p); + rcu_read_unlock(); seq_printf(m, "State:\t%s\n" @@ -188,10 +192,7 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, "Gid:\t%d\t%d\t%d\t%d\n" "FDSize:\t%d\nGroups:\t", get_task_state(p), - task_tgid_nr_ns(p, ns), - task_numa_group_id(p), - pid_nr_ns(pid, ns), - ppid, tpid, + tgid, ngid, pid_nr_ns(pid, ns), ppid, tpid, from_kuid_munged(user_ns, cred->uid), from_kuid_munged(user_ns, cred->euid), from_kuid_munged(user_ns, cred->suid), @@ -201,7 +202,6 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, from_kgid_munged(user_ns, cred->sgid), from_kgid_munged(user_ns, cred->fsgid), max_fds); - rcu_read_unlock(); group_info = cred->group_info; for (g = 0; g < group_info->ngroups; g++) -- cgit v1.2.3 From abdba6e9ea6d3903c2b0618db720e17b3c1c705c Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 10 Dec 2014 15:45:18 -0800 Subject: proc: task_state: ptrace_parent() doesn't need pid_alive() check p->ptrace != 0 means that release_task(p) was not called, so pid_alive() buys nothing and we can remove this check. Other callers already use it directly without additional checks. Note: with or without this patch ptrace_parent() can return the pointer to the freed task, this will be explained/fixed later. Signed-off-by: Oleg Nesterov Cc: Aaron Tomlin Cc: Alexey Dobriyan Cc: "Eric W. Biederman" , Cc: Sterling Alexander Cc: Peter Zijlstra Cc: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/array.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) (limited to 'fs/proc/array.c') diff --git a/fs/proc/array.c b/fs/proc/array.c index 800e30f8f284..bd117d065b82 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -157,19 +157,18 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, struct user_namespace *user_ns = seq_user_ns(m); struct group_info *group_info; int g; + struct task_struct *tracer; const struct cred *cred; - pid_t ppid, tpid, tgid, ngid; + pid_t ppid, tpid = 0, tgid, ngid; unsigned int max_fds = 0; rcu_read_lock(); ppid = pid_alive(p) ? task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0; - tpid = 0; - if (pid_alive(p)) { - struct task_struct *tracer = ptrace_parent(p); - if (tracer) - tpid = task_pid_nr_ns(tracer, ns); - } + + tracer = ptrace_parent(p); + if (tracer) + tpid = task_pid_nr_ns(tracer, ns); tgid = task_tgid_nr_ns(p, ns); ngid = task_numa_group_id(p); -- cgit v1.2.3