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authorEric W. Biederman <ebiederm@xmission.com>2017-07-16 22:05:57 -0500
committerEric W. Biederman <ebiederm@xmission.com>2018-07-21 10:43:12 -0500
commit019191342fecce4a461978a7191a43f313e19e86 (patch)
treeb256a747d10ad9b2b674a5466f366b5109cc6509 /fs/fcntl.c
parent6883f81aac6f44e7df70a6af189b3689ff52cbfb (diff)
downloadlwn-019191342fecce4a461978a7191a43f313e19e86.tar.gz
lwn-019191342fecce4a461978a7191a43f313e19e86.zip
signal: Use PIDTYPE_TGID to clearly store where file signals will be sent
When f_setown is called a pid and a pid type are stored. Replace the use of PIDTYPE_PID with PIDTYPE_TGID as PIDTYPE_TGID goes to the entire thread group. Replace the use of PIDTYPE_MAX with PIDTYPE_PID as PIDTYPE_PID now is only for a thread. Update the users of __f_setown to use PIDTYPE_TGID instead of PIDTYPE_PID. For now the code continues to capture task_pid (when task_tgid would really be appropriate), and iterate on PIDTYPE_PID (even when type == PIDTYPE_TGID) out of an abundance of caution to preserve existing behavior. Oleg Nesterov suggested using the test to ensure we use PIDTYPE_PID for tgid lookup also be used to avoid taking the tasklist lock. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'fs/fcntl.c')
-rw-r--r--fs/fcntl.c54
1 files changed, 32 insertions, 22 deletions
diff --git a/fs/fcntl.c b/fs/fcntl.c
index 12273b6ea56d..1523588fd759 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -116,7 +116,7 @@ int f_setown(struct file *filp, unsigned long arg, int force)
struct pid *pid = NULL;
int who = arg, ret = 0;
- type = PIDTYPE_PID;
+ type = PIDTYPE_TGID;
if (who < 0) {
/* avoid overflow below */
if (who == INT_MIN)
@@ -143,7 +143,7 @@ EXPORT_SYMBOL(f_setown);
void f_delown(struct file *filp)
{
- f_modown(filp, NULL, PIDTYPE_PID, 1);
+ f_modown(filp, NULL, PIDTYPE_TGID, 1);
}
pid_t f_getown(struct file *filp)
@@ -171,11 +171,11 @@ static int f_setown_ex(struct file *filp, unsigned long arg)
switch (owner.type) {
case F_OWNER_TID:
- type = PIDTYPE_MAX;
+ type = PIDTYPE_PID;
break;
case F_OWNER_PID:
- type = PIDTYPE_PID;
+ type = PIDTYPE_TGID;
break;
case F_OWNER_PGRP:
@@ -206,11 +206,11 @@ static int f_getown_ex(struct file *filp, unsigned long arg)
read_lock(&filp->f_owner.lock);
owner.pid = pid_vnr(filp->f_owner.pid);
switch (filp->f_owner.pid_type) {
- case PIDTYPE_MAX:
+ case PIDTYPE_PID:
owner.type = F_OWNER_TID;
break;
- case PIDTYPE_PID:
+ case PIDTYPE_TGID:
owner.type = F_OWNER_PID;
break;
@@ -785,20 +785,25 @@ void send_sigio(struct fown_struct *fown, int fd, int band)
read_lock(&fown->lock);
type = fown->pid_type;
- if (type == PIDTYPE_MAX) {
+ if (type == PIDTYPE_PID)
group = 0;
- type = PIDTYPE_PID;
- }
pid = fown->pid;
if (!pid)
goto out_unlock_fown;
-
- read_lock(&tasklist_lock);
- do_each_pid_task(pid, type, p) {
+
+ if (type <= PIDTYPE_TGID) {
+ rcu_read_lock();
+ p = pid_task(pid, PIDTYPE_PID);
send_sigio_to_task(p, fown, fd, band, group);
- } while_each_pid_task(pid, type, p);
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
+ } else {
+ read_lock(&tasklist_lock);
+ do_each_pid_task(pid, type, p) {
+ send_sigio_to_task(p, fown, fd, band, group);
+ } while_each_pid_task(pid, type, p);
+ read_unlock(&tasklist_lock);
+ }
out_unlock_fown:
read_unlock(&fown->lock);
}
@@ -821,22 +826,27 @@ int send_sigurg(struct fown_struct *fown)
read_lock(&fown->lock);
type = fown->pid_type;
- if (type == PIDTYPE_MAX) {
+ if (type == PIDTYPE_PID)
group = 0;
- type = PIDTYPE_PID;
- }
pid = fown->pid;
if (!pid)
goto out_unlock_fown;
ret = 1;
-
- read_lock(&tasklist_lock);
- do_each_pid_task(pid, type, p) {
+
+ if (type <= PIDTYPE_TGID) {
+ rcu_read_lock();
+ p = pid_task(pid, PIDTYPE_PID);
send_sigurg_to_task(p, fown, group);
- } while_each_pid_task(pid, type, p);
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
+ } else {
+ read_lock(&tasklist_lock);
+ do_each_pid_task(pid, type, p) {
+ send_sigurg_to_task(p, fown, group);
+ } while_each_pid_task(pid, type, p);
+ read_unlock(&tasklist_lock);
+ }
out_unlock_fown:
read_unlock(&fown->lock);
return ret;