From 019191342fecce4a461978a7191a43f313e19e86 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sun, 16 Jul 2017 22:05:57 -0500 Subject: 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 Signed-off-by: "Eric W. Biederman" --- fs/fcntl.c | 54 ++++++++++++++++++++++++++++++++---------------------- 1 file changed, 32 insertions(+), 22 deletions(-) (limited to 'fs/fcntl.c') 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; -- cgit