The patch titled
Fix locking for tty drivers when doing urgent characters
has been added to the -mm tree. Its filename is
fix-locking-for-tty-drivers-when-doing-urgent-characters.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Fix locking for tty drivers when doing urgent characters
From: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
If you send a priority character (as is done for flow control) then the tty
driver can either have its own method for "jumping the queue" or the characrer
can be queued normally. In the latter case we call the write method but
without the atomic_write_lock taken elsewhere.
Make this consistent. Note that the send_xchar method if implemented remains
outside of the lock as it can jump ahead of a current write so must not be
locked out by it.
Signed-off-by: Alan Cox <alan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/char/tty_ioctl.c | 18 +++++++++++-------
1 files changed, 11 insertions(+), 7 deletions(-)
diff -puN drivers/char/tty_ioctl.c~fix-locking-for-tty-drivers-when-doing-urgent-characters drivers/char/tty_ioctl.c
--- a/drivers/char/tty_ioctl.c~fix-locking-for-tty-drivers-when-doing-urgent-characters
+++ a/drivers/char/tty_ioctl.c
@@ -423,24 +423,28 @@ static int set_ltchars(struct tty_struct
*
* Send a high priority character to the tty even if stopped
*
- * Locking: none
- *
- * FIXME: overlapping calls with start/stop tty lose state of tty
+ * Locking: none for xchar method, write ordering for write method.
*/
-static void send_prio_char(struct tty_struct *tty, char ch)
+static int send_prio_char(struct tty_struct *tty, char ch)
{
int was_stopped = tty->stopped;
if (tty->driver->send_xchar) {
tty->driver->send_xchar(tty, ch);
- return;
+ return 0;
}
+
+ if (mutex_lock_interruptible(&tty->atomic_write_lock))
+ return -ERESTARTSYS;
+
if (was_stopped)
start_tty(tty);
tty->driver->write(tty, &ch, 1);
if (was_stopped)
stop_tty(tty);
+ mutex_unlock(&tty->atomic_write_lock);
+ return 0;
}
int n_tty_ioctl(struct tty_struct * tty, struct file * file,
@@ -514,11 +518,11 @@ int n_tty_ioctl(struct tty_struct * tty,
break;
case TCIOFF:
if (STOP_CHAR(tty) != __DISABLED_CHAR)
- send_prio_char(tty, STOP_CHAR(tty));
+ return send_prio_char(tty, STOP_CHAR(tty));
break;
case TCION:
if (START_CHAR(tty) != __DISABLED_CHAR)
- send_prio_char(tty, START_CHAR(tty));
+ return send_prio_char(tty, START_CHAR(tty));
break;
default:
return -EINVAL;
_
Patches currently in -mm which might be from alan@xxxxxxxxxxxxxxxxxxx are
git-libata-all.patch
libata-add-40pin-short-cable-support-honour-drive.patch
1-of-2-jmicron-driver.patch
1-of-2-jmicron-driver-fix.patch
2-of-2-jmicron-driver-plumbing-and-quirk.patch
non-libata-driver-for-jmicron-devices.patch
via-pata-controller-xfer-fixes.patch
via-pata-controller-xfer-fixes-fix.patch
megaraid-gcc-41-warning-fix.patch
voyager-tty-locking.patch
edac-new-opteron-athlon64-memory-controller-driver.patch
edac-new-opteron-athlon64-memory-controller-driver-tidy.patch
sanitize-3c589_cs.patch
make-prot_write-imply-prot_read.patch
remove-unused-tty_struct-variable.patch
there-is-no-devfs-there-has-never-been-a-devfs-we-have.patch
tty-locking-on-resize.patch
ahci-ati-sb600-sata-support-for-various-modes.patch
atiixp-ati-sb600-ide-support-for-various-modes.patch
dquot-add-proper-locking-when-using-current-signal-tty.patch
tty-trivial-kzalloc-opportunity.patch
tty-lock-ticogwinsz.patch
tty-stop-the-tty-vanishing-under-procfs-access.patch
exit-fix-crash-case.patch
tty-make-termios_sem-a-mutex.patch
tty-make-termios_sem-a-mutex-fix.patch
solaris-emulation-incorrect-tty-locking.patch
tty-fix-bits-and-note-more-bits-to-fix.patch
build-sound-sound_firmwarec-only-for-oss.patch
build-sound-sound_firmwarec-only-for-oss-doc.patch
generic_serial-remove-private-decoding-of-baud-rate-bits.patch
istallion-remove-private-baud-rate-decoding-which-is.patch
switch-mxser-and-moxa-from-hand-decoding-speeds.patch
specialix-remove-private-speed-decoding.patch
fix-locking-for-tty-drivers-when-doing-urgent-characters.patch
support-piping-into-commands-in-proc-sys-kernel-core_pattern.patch
support-piping-into-commands-in-proc-sys-kernel-core_pattern-fix-2.patch
ide-claim-extra-dma-ports-regardless-of-channel.patch
ide-always-release-dma-engine.patch
ide-error-handling-fixes.patch
ide-hpt3xxn-clocking-fixes.patch
ide-fix-hpt37x-timing-tables.patch
ide-optimize-hpt37x-timing-tables.patch
ide-fix-hpt3xx-hotswap-support.patch
ide-fix-the-case-of-multiple-hpt3xx-chips-present.patch
ide-hpt3xx-fix-pci-clock-detection.patch
ide-hpt3xx-fix-pci-clock-detection-fix-2.patch
piix-fix-82371mx-enablebits.patch
piix-remove-check-for-broken-mw-dma-mode-0.patch
piix-slc90e66-pio-mode-fallback-fix.patch
make-number-of-ide-interfaces-configurable.patch
ide_dma_speed-fixes.patch
hpt3xx-rework-rate-filtering.patch
hpt3xx-rework-rate-filtering-tidy.patch
hpt3xx-print-the-real-chip-name-at-startup.patch
hpt3xx-switch-to-using-pci_get_slot.patch
hpt3xx-cache-channels-mcr-address.patch
hpt3x7-merge-speedproc-handlers.patch
hpt370-clean-up-dma-timeout-handling.patch
enable-cdrom-dma-access-with-pdc20265_old.patch
ide-fix-revision-comparison-in-ide_in_drive_list.patch
ide-backport-piix-fixes-from-libata-into-the-legacy-driver.patch
hpt3xx-init-code-rewrite.patch
move-ide-to-unmaintained-drop-reference-to-old-git-tree.patch
drivers-ide-cleanups.patch
ide-remove-dma_base2-field-from-ide_hwif_t.patch
ide-reprogram-disk-pio-timings-on-resume.patch
config_pm=n-slim-drivers-ide-pci-sc1200c.patch
sstfb-clean-ups.patch
pci_module_init-convertion-in-ata_genericc.patch
pci_module_init-convertion-in-ata_genericc-fix.patch
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