Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=04a2e6a5cbf84e85fe86de0a18f6509b147e1d89
Commit: 04a2e6a5cbf84e85fe86de0a18f6509b147e1d89
Parent: 8d42db189ca99703f0f4f91c477cb54808c8eaaa
Author: Eric W. Biederman <[EMAIL PROTECTED]>
AuthorDate: Mon Feb 12 00:52:56 2007 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon Feb 12 09:48:31 2007 -0800
[PATCH] pid: make session_of_pgrp use struct pid instead of pid_t
To properly implement a pid namespace I need to deal exclusively in terms of
struct pid, because pid_t values become ambiguous.
To this end session_of_pgrp is transformed to take and return a struct pid
pointer. To avoid the need to worry about reference counting I now require
my
caller to hold the appropriate locks. Leaving callers repsonsible for
increasing the reference count if they need access to the result outside of
the locks.
Since session_of_pgrp currently only has one caller and that caller simply
uses only test the result for equality with another process group, the
locking
change means I don't actually have to acquire the tasklist_lock at all.
tiocspgrp is also modified to take and release the lock. The logic there
is a
little more complicated but nothing I won't need when I convert pgrp of a
tty
to a struct pid pointer.
Signed-off-by: Eric W. Biederman <[EMAIL PROTECTED]>
Cc: Alan Cox <[EMAIL PROTECTED]>
Cc: Oleg Nesterov <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
drivers/char/tty_io.c | 24 +++++++++++++++++-------
include/linux/kernel.h | 3 ++-
kernel/exit.c | 16 +++++++---------
3 files changed, 26 insertions(+), 17 deletions(-)
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index abfe24d..95f3596 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2990,7 +2990,8 @@ static int tiocgpgrp(struct tty_struct *tty, struct
tty_struct *real_tty, pid_t
static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty,
pid_t __user *p)
{
- pid_t pgrp;
+ struct pid *pgrp;
+ pid_t pgrp_nr;
int retval = tty_check_change(real_tty);
if (retval == -EIO)
@@ -3001,14 +3002,23 @@ static int tiocspgrp(struct tty_struct *tty, struct
tty_struct *real_tty, pid_t
(current->signal->tty != real_tty) ||
(real_tty->session != process_session(current)))
return -ENOTTY;
- if (get_user(pgrp, p))
+ if (get_user(pgrp_nr, p))
return -EFAULT;
- if (pgrp < 0)
+ if (pgrp_nr < 0)
return -EINVAL;
- if (session_of_pgrp(pgrp) != process_session(current))
- return -EPERM;
- real_tty->pgrp = pgrp;
- return 0;
+ rcu_read_lock();
+ pgrp = find_pid(pgrp_nr);
+ retval = -ESRCH;
+ if (!pgrp)
+ goto out_unlock;
+ retval = -EPERM;
+ if (session_of_pgrp(pgrp) != task_session(current))
+ goto out_unlock;
+ retval = 0;
+ real_tty->pgrp = pgrp_nr;
+out_unlock:
+ rcu_read_unlock();
+ return retval;
}
/**
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 3531764..9ddf25c 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -134,7 +134,8 @@ extern unsigned long long memparse(char *ptr, char
**retptr);
extern int core_kernel_text(unsigned long addr);
extern int __kernel_text_address(unsigned long addr);
extern int kernel_text_address(unsigned long addr);
-extern int session_of_pgrp(int pgrp);
+struct pid;
+extern struct pid *session_of_pgrp(struct pid *pgrp);
extern void dump_thread(struct pt_regs *regs, struct user *dump);
diff --git a/kernel/exit.c b/kernel/exit.c
index 14f1703..3ac6a7a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -185,21 +185,19 @@ repeat:
* This checks not only the pgrp, but falls back on the pid if no
* satisfactory pgrp is found. I dunno - gdb doesn't work correctly
* without this...
+ *
+ * The caller must hold rcu lock or the tasklist lock.
*/
-int session_of_pgrp(int pgrp)
+struct pid *session_of_pgrp(struct pid *pgrp)
{
struct task_struct *p;
- int sid = 0;
-
- read_lock(&tasklist_lock);
+ struct pid *sid = NULL;
- p = find_task_by_pid_type(PIDTYPE_PGID, pgrp);
+ p = pid_task(pgrp, PIDTYPE_PGID);
if (p == NULL)
- p = find_task_by_pid(pgrp);
+ p = pid_task(pgrp, PIDTYPE_PID);
if (p != NULL)
- sid = process_session(p);
-
- read_unlock(&tasklist_lock);
+ sid = task_session(p);
return sid;
}
-
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