fix setpriority(PRIO_PGRP) thread iterator breakage

When user calls sys_setpriority(PRIO_PGRP ...) on a NPTL style multi-LWP
process, only the task leader of the process is affected, all other
sibling LWP threads didn't receive the setting.  The problem was that the
iterator used in sys_setpriority() only iteartes over one task for each
process, ignoring all other sibling thread.

Introduce a new macro do_each_pid_thread / while_each_pid_thread to walk
each thread of a process.  Convert 4 call sites in {set/get}priority and
ioprio_{set/get}.

Signed-off-by: Ken Chen <kenchen@google.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/ioprio.c b/fs/ioprio.c
index c4a1c3c65aac35ba999a4739fb3ed6549b5e1b75..da3cc460d4df4d16f3afb81fea786589948a2c18 100644 (file)
--- a/fs/ioprio.c
+++ b/fs/ioprio.c
@@ -115,11 +115,11 @@ asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
                                pgrp = task_pgrp(current);
                        else
                                pgrp = find_vpid(who);
-                       do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
+                       do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
                                ret = set_task_ioprio(p, ioprio);
                                if (ret)
                                        break;
-                       } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
+                       } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
                        break;
                case IOPRIO_WHO_USER:
                        if (!who)
@@ -204,7 +204,7 @@ asmlinkage long sys_ioprio_get(int which, int who)
                                pgrp = task_pgrp(current);
                        else
                                pgrp = find_vpid(who);
-                       do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
+                       do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
                                tmpio = get_task_ioprio(p);
                                if (tmpio < 0)
                                        continue;
@@ -212,7 +212,7 @@ asmlinkage long sys_ioprio_get(int which, int who)
                                        ret = tmpio;
                                else
                                        ret = ioprio_best(ret, tmpio);
-                       } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
+                       } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
                        break;
                case IOPRIO_WHO_USER:
                        if (!who)

diff --git a/include/linux/pid.h b/include/linux/pid.h
index 22921ac4cfd948b88e10a06c0725b33363b38caf..d7e98ff8021eb3bfc38e4c851b425c7eac5c097f 100644 (file)
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -161,4 +161,13 @@ pid_t pid_vnr(struct pid *pid);
                        }                                               \
        } while (0)
 
+#define do_each_pid_thread(pid, type, task)                            \
+       do_each_pid_task(pid, type, task) {                             \
+               struct task_struct *tg___ = task;                       \
+               do {
+
+#define while_each_pid_thread(pid, type, task)                         \
+               } while_each_thread(tg___, task);                       \
+               task = tg___;                                           \
+       } while_each_pid_task(pid, type, task)
 #endif /* _LINUX_PID_H */

diff --git a/kernel/sys.c b/kernel/sys.c
index 3dacb00a7f765977c92d896ca4556f93ff87616b..038a7bc0901d20f90f841c5e4326fc1f2f2b963f 100644 (file)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -169,9 +169,9 @@ asmlinkage long sys_setpriority(int which, int who, int niceval)
                                pgrp = find_vpid(who);
                        else
                                pgrp = task_pgrp(current);
-                       do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
+                       do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
                                error = set_one_prio(p, niceval, error);
-                       } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
+                       } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
                        break;
                case PRIO_USER:
                        user = current->user;
@@ -229,11 +229,11 @@ asmlinkage long sys_getpriority(int which, int who)
                                pgrp = find_vpid(who);
                        else
                                pgrp = task_pgrp(current);
-                       do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
+                       do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
                                niceval = 20 - task_nice(p);
                                if (niceval > retval)
                                        retval = niceval;
-                       } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
+                       } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
                        break;
                case PRIO_USER:
                        user = current->user;