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ALPHA: srmcons, fix racy singleton structure 

The test and the assignment were racy. Make it really a singleton.
This is achieved by one global variable initialized at the module
init.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby 2012-03-05 14:51:58 +01:00 committed by Greg Kroah-Hartman
parent 5e88e6c4e8
commit ee024d494a
1 changed files with 5 additions and 35 deletions
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40
arch/alpha/kernel/srmcons.c
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@ -33,7 +33,7 @@ struct srmcons_private {
struct tty_struct *tty;
struct timer_list timer;
spinlock_t lock;
};
} srmcons_singleton;
typedef union _srmcons_result {
struct {
@ -153,44 +153,11 @@ srmcons_chars_in_buffer(struct tty_struct *tty)
return 0;
}
static int
srmcons_get_private_struct(struct srmcons_private **ps)
{
static struct srmcons_private *srmconsp = NULL;
static DEFINE_SPINLOCK(srmconsp_lock);
unsigned long flags;
int retval = 0;
if (srmconsp == NULL) {
srmconsp = kmalloc(sizeof(*srmconsp), GFP_KERNEL);
spin_lock_irqsave(&srmconsp_lock, flags);
if (srmconsp == NULL)
retval = -ENOMEM;
else {
srmconsp->tty = NULL;
spin_lock_init(&srmconsp->lock);
setup_timer(&srmconsp->timer, srmcons_receive_chars,
(unsigned long)srmconsp);
}
spin_unlock_irqrestore(&srmconsp_lock, flags);
}
*ps = srmconsp;
return retval;
}
static int
srmcons_open(struct tty_struct *tty, struct file *filp)
{
struct srmcons_private *srmconsp;
struct srmcons_private *srmconsp = &srmcons_singleton;
unsigned long flags;
int retval;
retval = srmcons_get_private_struct(&srmconsp);
if (retval)
return retval;
spin_lock_irqsave(&srmconsp->lock, flags);
@ -236,6 +203,9 @@ static const struct tty_operations srmcons_ops = {
static int __init
srmcons_init(void)
{
spin_lock_init(&srmcons_singleton.lock);
setup_timer(&srmcons_singleton.timer, srmcons_receive_chars,
(unsigned long)&srmcons_singleton);
if (srm_is_registered_console) {
struct tty_driver *driver;
int err;