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Subject[PATCH 3/4] 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 <oleg@redhat.com>
---
fs/proc/array.c | 12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 7c8d9ae..800e30f 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++)
--
1.5.5.1


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