The patch titled
8250: fix possible deadlock between serial8250_handle_port() and serial8250_interrupt()
has been added to the -mm tree. Its filename is
8250-fix-possible-deadlock-between-serial8250_handle_port-and-serial8250_interrupt.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: 8250: fix possible deadlock between serial8250_handle_port() and serial8250_interrupt()
From: Jiri Kosina <jkosina@xxxxxxx>
Commit 40b36daa introduced possibility that serial8250_backup_timeout() ->
serial8250_handle_port() locks port.lock without disabling irqs, thus
allowing deadlock against interrupt handler (port.lock is acquired in
serial8250_interrupt()).
Spotted by lockdep.
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
Cc: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Cc: Alex Williamson <alex.williamson@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/serial/8250.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
diff -puN drivers/serial/8250.c~8250-fix-possible-deadlock-between-serial8250_handle_port-and-serial8250_interrupt drivers/serial/8250.c
--- a/drivers/serial/8250.c~8250-fix-possible-deadlock-between-serial8250_handle_port-and-serial8250_interrupt
+++ a/drivers/serial/8250.c
@@ -1334,8 +1334,9 @@ static inline void
serial8250_handle_port(struct uart_8250_port *up)
{
unsigned int status;
+ unsigned long flags;
- spin_lock(&up->port.lock);
+ spin_lock_irqsave(&up->port.lock, flags);
status = serial_inp(up, UART_LSR);
@@ -1347,7 +1348,7 @@ serial8250_handle_port(struct uart_8250_
if (status & UART_LSR_THRE)
transmit_chars(up);
- spin_unlock(&up->port.lock);
+ spin_unlock_irqrestore(&up->port.lock, flags);
}
/*
_
Patches currently in -mm which might be from jkosina@xxxxxxx are
8250-fix-possible-deadlock-between-serial8250_handle_port-and-serial8250_interrupt.patch
git-hid.patch
git-ipwireless_cs.patch
-
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