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authorAlan Cox <alan@lxorguk.ukuu.org.uk>2008-04-30 11:53:29 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-30 19:29:40 +0400
commit04f378b198da233ca0aca341b113dc6579d46123 (patch)
tree696e7bd401125cee71ecaa2047c4273f38732554 /drivers/char/n_r3964.c
parente52384426064bca0669a954736206adca7595d48 (diff)
downloadlinux-04f378b198da233ca0aca341b113dc6579d46123.tar.xz
tty: BKL pushdown
- Push the BKL down into the line disciplines - Switch the tty layer to unlocked_ioctl - Introduce a new ctrl_lock spin lock for the control bits - Eliminate much of the lock_kernel use in n_tty - Prepare to (but don't yet) call the drivers with the lock dropped on the paths that historically held the lock BKL now primarily protects open/close/ldisc change in the tty layer [jirislaby@gmail.com: a couple of fixes] Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Jiri Slaby <jirislaby@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char/n_r3964.c')
-rw-r--r--drivers/char/n_r3964.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/char/n_r3964.c b/drivers/char/n_r3964.c
index 6b918b80f73e..3f6486e9f1ec 100644
--- a/drivers/char/n_r3964.c
+++ b/drivers/char/n_r3964.c
@@ -1075,12 +1075,15 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
TRACE_L("read()");
+ lock_kernel();
+
pClient = findClient(pInfo, task_pid(current));
if (pClient) {
pMsg = remove_msg(pInfo, pClient);
if (pMsg == NULL) {
/* no messages available. */
if (file->f_flags & O_NONBLOCK) {
+ unlock_kernel();
return -EAGAIN;
}
/* block until there is a message: */
@@ -1090,8 +1093,10 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
/* If we still haven't got a message, we must have been signalled */
- if (!pMsg)
+ if (!pMsg) {
+ unlock_kernel();
return -EINTR;
+ }
/* deliver msg to client process: */
theMsg.msg_id = pMsg->msg_id;
@@ -1102,12 +1107,15 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
kfree(pMsg);
TRACE_M("r3964_read - msg kfree %p", pMsg);
- if (copy_to_user(buf, &theMsg, count))
+ if (copy_to_user(buf, &theMsg, count)) {
+ unlock_kernel();
return -EFAULT;
+ }
TRACE_PS("read - return %d", count);
return count;
}
+ unlock_kernel();
return -EPERM;
}
@@ -1156,6 +1164,8 @@ static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
pHeader->locks = 0;
pHeader->owner = NULL;
+ lock_kernel();
+
pClient = findClient(pInfo, task_pid(current));
if (pClient) {
pHeader->owner = pClient;
@@ -1173,6 +1183,8 @@ static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
add_tx_queue(pInfo, pHeader);
trigger_transmit(pInfo);
+ unlock_kernel();
+
return 0;
}