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authorAlan Cox <alan@lxorguk.ukuu.org.uk>2006-02-14 12:50:54 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-14 13:01:39 -0500
commit5552c28f6937d2a2b873d06c6d09b96204722dd0 (patch)
tree041a8ba94166d9c75c34dc385d5298ae4d59d9fe /drivers/char/esp.c
parent303794400992b907b7cac0d91788603636c7e0fe (diff)
[PATCH] Fix locking error in esp
Noted by Al Viro. Also remove unused tmp_buf Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/char/esp.c')
-rw-r--r--drivers/char/esp.c22
1 files changed, 2 insertions, 20 deletions
diff --git a/drivers/char/esp.c b/drivers/char/esp.c
index 57539d8f9f7c..09dc4b01232c 100644
--- a/drivers/char/esp.c
+++ b/drivers/char/esp.c
@@ -150,17 +150,6 @@ static void rs_wait_until_sent(struct tty_struct *, int);
150/* Standard COM flags (except for COM4, because of the 8514 problem) */ 150/* Standard COM flags (except for COM4, because of the 8514 problem) */
151#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST) 151#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST)
152 152
153/*
154 * tmp_buf is used as a temporary buffer by serial_write. We need to
155 * lock it in case the memcpy_fromfs blocks while swapping in a page,
156 * and some other program tries to do a serial write at the same time.
157 * Since the lock will only come under contention when the system is
158 * swapping and available memory is low, it makes sense to share one
159 * buffer across all the serial ports, since it significantly saves
160 * memory if large numbers of serial ports are open.
161 */
162static unsigned char *tmp_buf;
163
164static inline int serial_paranoia_check(struct esp_struct *info, 153static inline int serial_paranoia_check(struct esp_struct *info,
165 char *name, const char *routine) 154 char *name, const char *routine)
166{ 155{
@@ -1267,7 +1256,7 @@ static int rs_write(struct tty_struct * tty,
1267 if (serial_paranoia_check(info, tty->name, "rs_write")) 1256 if (serial_paranoia_check(info, tty->name, "rs_write"))
1268 return 0; 1257 return 0;
1269 1258
1270 if (!tty || !info->xmit_buf || !tmp_buf) 1259 if (!tty || !info->xmit_buf)
1271 return 0; 1260 return 0;
1272 1261
1273 while (1) { 1262 while (1) {
@@ -2291,11 +2280,7 @@ static int esp_open(struct tty_struct *tty, struct file * filp)
2291 tty->driver_data = info; 2280 tty->driver_data = info;
2292 info->tty = tty; 2281 info->tty = tty;
2293 2282
2294 if (!tmp_buf) { 2283 spin_unlock_irqrestore(&info->lock, flags);
2295 tmp_buf = (unsigned char *) get_zeroed_page(GFP_KERNEL);
2296 if (!tmp_buf)
2297 return -ENOMEM;
2298 }
2299 2284
2300 /* 2285 /*
2301 * Start up serial port 2286 * Start up serial port
@@ -2602,9 +2587,6 @@ static void __exit espserial_exit(void)
2602 free_pages((unsigned long)dma_buffer, 2587 free_pages((unsigned long)dma_buffer,
2603 get_order(DMA_BUFFER_SZ)); 2588 get_order(DMA_BUFFER_SZ));
2604 2589
2605 if (tmp_buf)
2606 free_page((unsigned long)tmp_buf);
2607
2608 while (free_pio_buf) { 2590 while (free_pio_buf) {
2609 pio_buf = free_pio_buf->next; 2591 pio_buf = free_pio_buf->next;
2610 kfree(free_pio_buf); 2592 kfree(free_pio_buf);