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Subject[PATCH 1/3] Char: mxser_new, fix recursive locking
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Andrew, I think it would be good to have these 3 in 2.6.21.

--
mxser_new, fix recursive locking

Acquire a port lock only if not in_interrupt in some places, because ISR
holds the lock yet (and ldisc calls some of driver's routines which tries to
acquire it again due to tty->low_latency).

Thanks to Jan "Yenya" Kasprzak.

Cc: Jan "Yenya" Kasprzak <kas@fi.muni.cz>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>

---
commit a3c71212efb38a67d344f35137136808e64537c6
tree c1ec123ca7007190dfae8c06fafec4702d88e00c
parent 0156510dee9d326af2ec52cf8b1a388ce9a839e9
author Jiri Slaby <jirislaby@gmail.com> Mon, 16 Apr 2007 13:24:46 +0200
committer Jiri Slaby <jirislaby@gmail.com> Mon, 16 Apr 2007 13:24:46 +0200
drivers/char/mxser_new.c | 46 ++++++++++++++++++++++++++++------------------
1 files changed, 28 insertions(+), 18 deletions(-)
diff --git a/drivers/char/mxser_new.c b/drivers/char/mxser_new.c
index 6362e78..626f491 100644
--- a/drivers/char/mxser_new.c
+++ b/drivers/char/mxser_new.c
@@ -85,6 +85,16 @@
#define MXSER_HIGHBAUD 1
#define MXSER_HAS2 2

+/* if we are in interrupt, lock is held by ISR, don't acquire it again! */
+#define mx_lock(info, flags) do { \
+ if (!in_interrupt()) \
+ spin_lock_irqsave(&(info)->slock, flags); \
+} while (0)
+#define mx_unlock(info, flags) do { \
+ if (!in_interrupt()) \
+ spin_unlock_irqrestore(&(info)->slock, flags); \
+} while (0)
+
/* This is only for PCI */
static const struct {
int type;
@@ -869,7 +879,7 @@ static void mxser_shutdown(struct mxser_port *info)
if (!(info->flags & ASYNC_INITIALIZED))
return;

- spin_lock_irqsave(&info->slock, flags);
+ mx_lock(info, flags);

/*
* clear delta_msr_wait queue to avoid mem leaks: we may free the irq
@@ -912,7 +922,7 @@ static void mxser_shutdown(struct mxser_port *info)
if (info->board->chip_flag)
SET_MOXA_MUST_NO_SOFTWARE_FLOW_CONTROL(info->ioaddr);

- spin_unlock_irqrestore(&info->slock, flags);
+ mx_unlock(info, flags);
}

/*
@@ -1076,11 +1086,11 @@ static int mxser_write(struct tty_struct *tty, const unsigned char *buf, int cou
break;

memcpy(info->xmit_buf + info->xmit_head, buf, c);
- spin_lock_irqsave(&info->slock, flags);
+ mx_lock(info, flags);
info->xmit_head = (info->xmit_head + c) &
(SERIAL_XMIT_SIZE - 1);
info->xmit_cnt += c;
- spin_unlock_irqrestore(&info->slock, flags);
+ mx_unlock(info, flags);

buf += c;
count -= c;
@@ -1091,12 +1101,12 @@ static int mxser_write(struct tty_struct *tty, const unsigned char *buf, int cou
if (!tty->hw_stopped ||
(info->type == PORT_16550A) ||
(info->board->chip_flag)) {
- spin_lock_irqsave(&info->slock, flags);
+ mx_lock(info, flags);
outb(info->IER & ~UART_IER_THRI, info->ioaddr +
UART_IER);
info->IER |= UART_IER_THRI;
outb(info->IER, info->ioaddr + UART_IER);
- spin_unlock_irqrestore(&info->slock, flags);
+ mx_unlock(info, flags);
}
}
return total;
@@ -1113,20 +1123,20 @@ static void mxser_put_char(struct tty_struct *tty, unsigned char ch)
if (info->xmit_cnt >= SERIAL_XMIT_SIZE - 1)
return;

- spin_lock_irqsave(&info->slock, flags);
+ mx_lock(info, flags);
info->xmit_buf[info->xmit_head++] = ch;
info->xmit_head &= SERIAL_XMIT_SIZE - 1;
info->xmit_cnt++;
- spin_unlock_irqrestore(&info->slock, flags);
+ mx_unlock(info, flags);
if (!tty->stopped) {
if (!tty->hw_stopped ||
(info->type == PORT_16550A) ||
info->board->chip_flag) {
- spin_lock_irqsave(&info->slock, flags);
+ mx_lock(info, flags);
outb(info->IER & ~UART_IER_THRI, info->ioaddr + UART_IER);
info->IER |= UART_IER_THRI;
outb(info->IER, info->ioaddr + UART_IER);
- spin_unlock_irqrestore(&info->slock, flags);
+ mx_unlock(info, flags);
}
}
}
@@ -1146,13 +1156,13 @@ static void mxser_flush_chars(struct tty_struct *tty)
))
return;

- spin_lock_irqsave(&info->slock, flags);
+ mx_lock(info, flags);

outb(info->IER & ~UART_IER_THRI, info->ioaddr + UART_IER);
info->IER |= UART_IER_THRI;
outb(info->IER, info->ioaddr + UART_IER);

- spin_unlock_irqrestore(&info->slock, flags);
+ mx_unlock(info, flags);
}

static int mxser_write_room(struct tty_struct *tty)
@@ -1179,7 +1189,7 @@ static void mxser_flush_buffer(struct tty_struct *tty)
unsigned long flags;


- spin_lock_irqsave(&info->slock, flags);
+ mx_lock(info, flags);
info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;

fcr = inb(info->ioaddr + UART_FCR);
@@ -1187,7 +1197,7 @@ static void mxser_flush_buffer(struct tty_struct *tty)
info->ioaddr + UART_FCR);
outb(fcr, info->ioaddr + UART_FCR);

- spin_unlock_irqrestore(&info->slock, flags);
+ mx_unlock(info, flags);

tty_wakeup(tty);
}
@@ -1983,12 +1993,12 @@ static void mxser_stop(struct tty_struct *tty)
struct mxser_port *info = tty->driver_data;
unsigned long flags;

- spin_lock_irqsave(&info->slock, flags);
+ mx_lock(info, flags);
if (info->IER & UART_IER_THRI) {
info->IER &= ~UART_IER_THRI;
outb(info->IER, info->ioaddr + UART_IER);
}
- spin_unlock_irqrestore(&info->slock, flags);
+ mx_unlock(info, flags);
}

static void mxser_start(struct tty_struct *tty)
@@ -1996,13 +2006,13 @@ static void mxser_start(struct tty_struct *tty)
struct mxser_port *info = tty->driver_data;
unsigned long flags;

- spin_lock_irqsave(&info->slock, flags);
+ mx_lock(info, flags);
if (info->xmit_cnt && info->xmit_buf) {
outb(info->IER & ~UART_IER_THRI, info->ioaddr + UART_IER);
info->IER |= UART_IER_THRI;
outb(info->IER, info->ioaddr + UART_IER);
}
- spin_unlock_irqrestore(&info->slock, flags);
+ mx_unlock(info, flags);
}

static void mxser_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
-
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