1 files changed, 29 insertions, 23 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 83396ab14998..dd31e3b6bf77 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1153,11 +1153,10 @@ err_unlock:
 static ssize_t oom_adj_write(struct file *file, const char __user *buf,
 			     size_t count, loff_t *ppos)
 {
-	char buffer[PROC_NUMBUF];
+	char buffer[PROC_NUMBUF] = {};
 	int oom_adj;
 	int err;
 
-	memset(buffer, 0, sizeof(buffer));
 	if (count > sizeof(buffer) - 1)
 		count = sizeof(buffer) - 1;
 	if (copy_from_user(buffer, buf, count)) {
@@ -1213,11 +1212,10 @@ static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
 static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
 					size_t count, loff_t *ppos)
 {
-	char buffer[PROC_NUMBUF];
+	char buffer[PROC_NUMBUF] = {};
 	int oom_score_adj;
 	int err;
 
-	memset(buffer, 0, sizeof(buffer));
 	if (count > sizeof(buffer) - 1)
 		count = sizeof(buffer) - 1;
 	if (copy_from_user(buffer, buf, count)) {
@@ -1358,13 +1356,13 @@ static ssize_t proc_fault_inject_write(struct file * file,
 			const char __user * buf, size_t count, loff_t *ppos)
 {
 	struct task_struct *task;
-	char buffer[PROC_NUMBUF];
+	char buffer[PROC_NUMBUF] = {};
 	int make_it_fail;
 	int rv;
 
 	if (!capable(CAP_SYS_RESOURCE))
 		return -EPERM;
-	memset(buffer, 0, sizeof(buffer));
+
 	if (count > sizeof(buffer) - 1)
 		count = sizeof(buffer) - 1;
 	if (copy_from_user(buffer, buf, count))
@@ -1509,11 +1507,10 @@ sched_autogroup_write(struct file *file, const char __user *buf,
 {
 	struct inode *inode = file_inode(file);
 	struct task_struct *p;
-	char buffer[PROC_NUMBUF];
+	char buffer[PROC_NUMBUF] = {};
 	int nice;
 	int err;
 
-	memset(buffer, 0, sizeof(buffer));
 	if (count > sizeof(buffer) - 1)
 		count = sizeof(buffer) - 1;
 	if (copy_from_user(buffer, buf, count))
@@ -1666,10 +1663,9 @@ static ssize_t comm_write(struct file *file, const char __user *buf,
 {
 	struct inode *inode = file_inode(file);
 	struct task_struct *p;
-	char buffer[TASK_COMM_LEN];
+	char buffer[TASK_COMM_LEN] = {};
 	const size_t maxlen = sizeof(buffer) - 1;
 
-	memset(buffer, 0, sizeof(buffer));
 	if (copy_from_user(buffer, buf, count > maxlen ? maxlen : count))
 		return -EFAULT;
 
@@ -2976,8 +2972,7 @@ static const struct file_operations proc_coredump_filter_operations = {
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 static int do_io_accounting(struct task_struct *task, struct seq_file *m, int whole)
 {
-	struct task_io_accounting acct = task->ioac;
-	unsigned long flags;
+	struct task_io_accounting acct;
 	int result;
 
 	result = down_read_killable(&task->signal->exec_update_lock);
@@ -2989,15 +2984,28 @@ static int do_io_accounting(struct task_struct *task, struct seq_file *m, int wh
 		goto out_unlock;
 	}
 
-	if (whole && lock_task_sighand(task, &flags)) {
-		struct task_struct *t = task;
+	if (whole) {
+		struct signal_struct *sig = task->signal;
+		struct task_struct *t;
+		unsigned int seq = 1;
+		unsigned long flags;
+
+		rcu_read_lock();
+		do {
+			seq++; /* 2 on the 1st/lockless path, otherwise odd */
+			flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq);
 
-		task_io_accounting_add(&acct, &task->signal->ioac);
-		while_each_thread(task, t)
-			task_io_accounting_add(&acct, &t->ioac);
+			acct = sig->ioac;
+			__for_each_thread(sig, t)
+				task_io_accounting_add(&acct, &t->ioac);
 
-		unlock_task_sighand(task, &flags);
+		} while (need_seqretry(&sig->stats_lock, seq));
+		done_seqretry_irqrestore(&sig->stats_lock, seq, flags);
+		rcu_read_unlock();
+	} else {
+		acct = task->ioac;
 	}
+
 	seq_printf(m,
 		   "rchar: %llu\n"
 		   "wchar: %llu\n"
@@ -3818,7 +3826,7 @@ static struct task_struct *first_tid(struct pid *pid, int tid, loff_t f_pos,
 	for_each_thread(task, pos) {
 		if (!nr--)
 			goto found;
-	};
+	}
 fail:
 	pos = NULL;
 	goto out;
@@ -3840,10 +3848,8 @@ static struct task_struct *next_tid(struct task_struct *start)
 	struct task_struct *pos = NULL;
 	rcu_read_lock();
 	if (pid_alive(start)) {
-		pos = next_thread(start);
-		if (thread_group_leader(pos))
-			pos = NULL;
-		else
+		pos = __next_thread(start);
+		if (pos)
 			get_task_struct(pos);
 	}
 	rcu_read_unlock();