Re: [PATCH] tty: getting rid of __GFP_NOFAIL in tty_add_file
From: Jiri Olsa
Date: Fri Sep 03 2010 - 09:15:46 EST
On Thu, Sep 02, 2010 at 01:09:50PM -0700, Greg KH wrote:
> On Thu, Sep 02, 2010 at 06:17:56PM +0200, Jiri Olsa wrote:
> > hi,
> >
> > added error handling for struct tty_file_private allocation,
> > Fixed error paths in tty_open and ptmx_open.
>
> Heh, look at the linux-next tree, there's already a patch from Pekka in
> there that does this, but in a little different way. Let me know if
> that version doesn't work for you.
cool ;)
I think the current error paths do not release some memory
- tty_struct in tty_open path
- tty_struct/dev_pts_index/inode in ptmx_open error paths
question is if that's a big deal in case we were not able to allocate
as much as struct tty_file_private..
I'm attaching my patch rebased for linux-next, but I would not mind
this one being omitted for the reason above.
thanks,
jirka
---
Added error handling for struct tty_file_private allocation,
Fixed error paths in tty_open and ptmx_open.
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
drivers/char/pty.c | 31 +++++++++++++++++------------
drivers/char/tty_io.c | 52 +++++++++++++++++++++++++++++++-----------------
include/linux/tty.h | 5 +++-
3 files changed, 55 insertions(+), 33 deletions(-)
diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index 923a485..08a449c 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -652,17 +652,24 @@ static const struct tty_operations pty_unix98_ops = {
static int ptmx_open(struct inode *inode, struct file *filp)
{
struct tty_struct *tty;
+ struct tty_file_private *priv;
int retval;
int index;
nonseekable_open(inode, filp);
+ priv = alloc_tty_priv();
+ if (!priv)
+ return -ENOMEM;
+
/* find a device that is not in use. */
tty_lock();
index = devpts_new_index(inode);
tty_unlock();
- if (index < 0)
+ if (index < 0) {
+ free_tty_priv(priv);
return index;
+ }
mutex_lock(&tty_mutex);
tty_lock();
@@ -671,32 +678,30 @@ static int ptmx_open(struct inode *inode, struct file *filp)
if (IS_ERR(tty)) {
retval = PTR_ERR(tty);
+ free_tty_priv(priv);
+ devpts_kill_index(inode, index);
goto out;
}
set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
-
- retval = tty_add_file(tty, filp);
- if (retval)
- goto out;
+ tty_set_priv(priv, tty, filp);
retval = devpts_pty_new(inode, tty->link);
if (retval)
- goto out1;
+ goto out_release;
retval = ptm_driver->ops->open(tty, filp);
if (retval)
- goto out2;
-out1:
- tty_unlock();
- return retval;
-out2:
+ goto out_release;
+
+out:
tty_unlock();
- tty_release(inode, filp);
return retval;
-out:
+
+out_release:
devpts_kill_index(inode, index);
tty_unlock();
+ tty_release(inode, filp);
return retval;
}
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index d6c659f..5071d01 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -195,35 +195,44 @@ static inline struct tty_struct *file_tty(struct file *file)
return ((struct tty_file_private *)file->private_data)->tty;
}
-/* Associate a new file with the tty structure */
-int tty_add_file(struct tty_struct *tty, struct file *file)
+struct tty_file_private *alloc_tty_priv(void)
{
struct tty_file_private *priv;
- priv = kmalloc(sizeof(*priv), GFP_KERNEL);
- if (!priv)
- return -ENOMEM;
+ priv = kmalloc(sizeof(struct tty_file_private), GFP_KERNEL);
+ if (priv)
+ INIT_LIST_HEAD(&priv->list);
+
+ return priv;
+}
+/* Associate a new file with the tty structure */
+void tty_set_priv(struct tty_file_private *priv, struct tty_struct *tty,
+ struct file *file)
+{
priv->tty = tty;
priv->file = file;
- file->private_data = priv;
spin_lock(&tty_files_lock);
list_add(&priv->list, &tty->tty_files);
spin_unlock(&tty_files_lock);
- return 0;
+ file->private_data = priv;
}
/* Delete file from its tty */
-void tty_del_file(struct file *file)
+void free_tty_priv(struct tty_file_private *priv)
{
- struct tty_file_private *priv = file->private_data;
+ if (!list_empty(&priv->list)) {
+ struct file *file = priv->file;
+
+ spin_lock(&tty_files_lock);
+ list_del(&priv->list);
+ spin_unlock(&tty_files_lock);
+
+ file->private_data = NULL;
+ }
- spin_lock(&tty_files_lock);
- list_del(&priv->list);
- spin_unlock(&tty_files_lock);
- file->private_data = NULL;
kfree(priv);
}
@@ -1713,7 +1722,7 @@ int tty_release(struct inode *inode, struct file *filp)
* - do_tty_hangup no longer sees this file descriptor as
* something that needs to be handled for hangups.
*/
- tty_del_file(filp);
+ free_tty_priv(filp->private_data);
/*
* Perform some housekeeping before deciding whether to return.
@@ -1792,6 +1801,7 @@ int tty_release(struct inode *inode, struct file *filp)
static int tty_open(struct inode *inode, struct file *filp)
{
struct tty_struct *tty = NULL;
+ struct tty_file_private *priv;
int noctty, retval;
struct tty_driver *driver;
int index;
@@ -1866,6 +1876,13 @@ got_driver:
}
}
+ priv = alloc_tty_priv();
+ if (!priv) {
+ tty_unlock();
+ mutex_unlock(&tty_mutex);
+ return -ENOMEM;
+ }
+
if (tty) {
retval = tty_reopen(tty);
if (retval)
@@ -1877,14 +1894,11 @@ got_driver:
tty_driver_kref_put(driver);
if (IS_ERR(tty)) {
tty_unlock();
+ free_tty_priv(priv);
return PTR_ERR(tty);
}
- retval = tty_add_file(tty, filp);
- if (retval) {
- tty_unlock();
- return retval;
- }
+ tty_set_priv(priv, tty, filp);
check_tty_count(tty, "tty_open");
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 86be0cd..1520a35 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -465,8 +465,11 @@ extern dev_t tty_devnum(struct tty_struct *tty);
extern void proc_clear_tty(struct task_struct *p);
extern struct tty_struct *get_current_tty(void);
extern void tty_default_fops(struct file_operations *fops);
+struct tty_file_private *alloc_tty_priv(void);
+void tty_set_priv(struct tty_file_private *priv, struct tty_struct *tty,
+ struct file *file);
+void free_tty_priv(struct tty_file_private *priv);
extern struct tty_struct *alloc_tty_struct(void);
-extern int tty_add_file(struct tty_struct *tty, struct file *file);
extern void free_tty_struct(struct tty_struct *tty);
extern void initialize_tty_struct(struct tty_struct *tty,
struct tty_driver *driver, int idx);
--
1.7.1
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