Char: moxa, serialise timer

- del timer after we are sure it won't be fired again
- make timer scheduling atomic
- don't reschedule timer when all cards have gone

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Tested-by: Oyvind Aabling <Oyvind.Aabling@uni-c.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 11 deletions

diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
index 797284fe5fce..abcc16eba44f 100644
--- a/drivers/char/moxa.c
+++ b/drivers/char/moxa.c
@@ -846,10 +846,11 @@ static int moxa_init_board(struct moxa_board_conf *brd, struct device *dev)
         if (ret)
                 goto err_free;
 
+        spin_lock_bh(&moxa_lock);
         brd->ready = 1;
-
         if (!timer_pending(&moxaTimer))
                 mod_timer(&moxaTimer, jiffies + HZ / 50);
+        spin_unlock_bh(&moxa_lock);
 
         return 0;
 err_free:
@@ -1041,13 +1042,6 @@ static void __exit moxa_exit(void)
 {
         int i;
 
-        del_timer_sync(&moxaTimer);
-
-        if (tty_unregister_driver(moxaDriver))
-                printk(KERN_ERR "Couldn't unregister MOXA Intellio family "
-                                "serial driver\n");
-        put_tty_driver(moxaDriver);
-
 #ifdef CONFIG_PCI
         pci_unregister_driver(&moxa_pci_driver);
 #endif
@@ -1055,6 +1049,13 @@ static void __exit moxa_exit(void)
         for (i = 0; i < MAX_BOARDS; i++) /* ISA boards */
                 if (moxa_boards[i].ready)
                         moxa_board_deinit(&moxa_boards[i]);
+
+        del_timer_sync(&moxaTimer);
+
+        if (tty_unregister_driver(moxaDriver))
+                printk(KERN_ERR "Couldn't unregister MOXA Intellio family "
+                                "serial driver\n");
+        put_tty_driver(moxaDriver);
 }
 
 module_init(moxa_init);
@@ -1432,7 +1433,7 @@ static void moxa_poll(unsigned long ignored)
 {
         struct moxa_board_conf *brd;
         u16 __iomem *ip;
-        unsigned int card, port;
+        unsigned int card, port, served = 0;
 
         spin_lock(&moxa_lock);
         for (card = 0; card < MAX_BOARDS; card++) {
@@ -1440,6 +1441,8 @@ static void moxa_poll(unsigned long ignored)
                 if (!brd->ready)
                         continue;
 
+                served++;
+
                 ip = NULL;
                 if (readb(brd->intPend) == 0xff)
                         ip = brd->intTable + readb(brd->intNdx);
@@ -1460,9 +1463,10 @@ static void moxa_poll(unsigned long ignored)
                 }
         }
         moxaLowWaterChk = 0;
-        spin_unlock(&moxa_lock);
 
-        mod_timer(&moxaTimer, jiffies + HZ / 50);
+        if (served)
+                mod_timer(&moxaTimer, jiffies + HZ / 50);
+        spin_unlock(&moxa_lock);
 }
 
 /******************************************************************************/