There are several pretty much unfixable races in the old ldisc code, especially
with respect to pty behaviour and also to hangup. It's easier to rewrite the
code than simply try and patch it up.
This patch
- splits the ldisc from the tty (so we will be able to refcount it more cleanly
later)
- introduces a mutex lock for ldisc changing on an active device
- fixes the complete mess that hangup caused
- implements hopefully correct setldisc/close/hangup locking
There are still some problems around pty pairs that have always been there but
at least it is now possible to understand the code and fix further problems.
This fixes the following known bugs
- hang up can leak ldisc references
- hang up may not call open/close on ldisc in a matched way
- pty/tty pairs can deadlock during an ldisc change
- reading the ldisc proc files can cause every ldisc to be loaded
and probably a few other of the mysterious ldisc race reports.
I'm sure it also adds the odd new one.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Before trying to tackle the ldisc bugs the code needs to be a good deal
more readable, so do the simple extractions of routines first.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The tty throttling code can race due to the lock drops. It takes very high
loads but this has been observed and verified by Rob Duncan.
The basic problem is that on an SMP box we can go
CPU #1 CPU #2
need to throttle ?
suppose we should buffer space cleared
are we throttled
yes ? - unthrottle
call throttle method
This changeet take the termios lock to protect against this. The termios
lock isn't the initial obvious candidate but many implementations of throttle
methods already need to poke around their own termios structures (and nobody
really locks them against a racing change of flow control).
This does mean that anyone who is setting tty->low_latency = 1 and then
calling tty_flip_buffer_push from their unthrottle method is going to end up
collapsing in a pile of locks. However we've removed all the known bogus
users of low_latency = 1 and such use isn't safe anyway for other reasons so
catching it would be an improvement.
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Define ASYNCB_* flags which are bit numbers of the ASYNC_* flags.
This is useful for {test,set,clear}_bit.
Also convert each ASYNC_% to be (1 << ASYNCB_%) and define masks
with the macros, not constants.
Tested with:
#include "PATH_TO_KERNEL/include/linux/serial.h"
static struct {
unsigned int new, old;
} as[] = {
{ ASYNC_HUP_NOTIFY, 0x0001 },
{ ASYNC_FOURPORT, 0x0002 },
...
{ ASYNC_BOOT_ONLYMCA, 0x00400000 },
{ ASYNC_INTERNAL_FLAGS, 0xFFC00000 }
};
...
for (a = 0; a < ARRAY_SIZE(as); a++)
if (as[a].old != as[a].new)
printf("%.8x != %.8x\n", as[a].old, as[a].new);
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove ugly all-over-the-code casts of ctl_addr to 9060 space.
Add an union to the cyclades_card structure, which contains
a pointer to both 9050 and 9060 spaces.
The 9050 space layout is unknown, so let it still as a void
__iomem pointer.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This allows us to clean stuff up, but is probably also going to cause
some app breakage with buggy apps as we now implement proper POSIX behaviour
for USB ports matching all the other ports. This does also mean other apps
that break on USB will now work properly.
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We need this for devices that cannot flush and wait, but which do not order
data and modem events. Without it we will hang up before all the data
clears the hardware. Needed for the USB changes.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some drivers implement this internally, others miss it out. Push the
behaviour into the core code as that way everyone will do it consistently.
Update the dtr rts method to raise or lower depending upon flags. Having a
single method in this style fits most of the implementations more cleanly than
two funtions.
We need this in place before we tackle the USB side
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* master.kernel.org:/home/rmk/linux-2.6-arm:
[ARM] 5543/1: arm: serial amba: add missing declaration in serial.h
[ARM] pxa: fix pxa27x_udc default pullup GPIO
[ARM] pxa/imote2: fix UCAM sensor board ADC model number
mx[23]: don't put clock lookups in __initdata
fix oops when using console=ttymxcN with N > 0
[ARM] ARMv7 errata: only apply fixes when running on applicable CPU
[ARM] 5534/1: kmalloc must return a cache line aligned buffer
This header is sometimes included in the uncompress stage to get
register values, but no <linux/amba/bus.h> can be included there.
So declare "struct amba_device" here before using it in a prototype.
Signed-off-by: Alessandro Rubini <rubini@unipv.it>
Acked-by: Andrea Gallo <andrea.gallo@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The "trace || CLONE_PTRACE" check in tracehook_report_clone() is not right,
- If the untraced task does clone(CLONE_PTRACE) the new child is not traced,
we must not queue SIGSTOP.
- If we forked the traced task, but the tracer exits and untraces both the
forking task and the new child (after copy_process() drops tasklist_lock),
we should not queue SIGSTOP too.
Change the code to check task_ptrace() != 0 instead. This is still racy, but
the race is harmless.
We can race with another tracer attaching to this child, or the tracer can
exit and detach in parallel. But giwen that we didn't do wake_up_new_task()
yet, the child must have the pending SIGSTOP anyway.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Making the drm_crtc.c code recognize the DPMS property and invoke the
connector->dpms function doesn't remove any capability from the driver while
reducing code duplication.
That just highlighted the problem with the existing DPMS functions which
could turn off the connector, but failed to turn off any relevant crtcs. The
new drm_helper_connector_dpms function manages all of that, using the
drm_helper-specific crtc and encoder dpms functions, automatically computing
the appropriate DPMS level for each object in the system.
This fixes the current troubles in the i915 driver which left PLLs, pipes
and planes running while in DPMS_OFF mode or even while they were unused.
Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Ideally we should have a directory of drivers and a link to the 'active'
driver. For now just show the first device which is effectively the existing
semantics without a warning.
This is an update on the original buggy patch that I then forgot to
resubmit. Confusingly it was proposed by Red Hat, written by Etched Pixels
fixed and submitted by Intel ...
Resolves-Bug: http://bugzilla.kernel.org/show_bug.cgi?id=9749
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fix the following 'make headers_check' warnings:
usr/include/linux/net_dropmon.h:7: found __[us]{8,16,32,64} type without #include <linux/types.h>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
fix the following 'make headers_check' warnings:
usr/include/linux/auto_fs.h:17: include of <linux/types.h> is preferred over <asm/types.h>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: libps2 - better handle bad scheduler decisions
Input: usb1400_ts - fix access to "device data" in resume function
Input: multitouch - augment event semantics documentation
Input: multitouch - add tracking ID to the protocol
mapping->tree_lock can be acquired from interrupt context. Then,
following dead lock can occur.
Assume "A" as a page.
CPU0:
lock_page_cgroup(A)
interrupted
-> take mapping->tree_lock.
CPU1:
take mapping->tree_lock
-> lock_page_cgroup(A)
This patch tries to fix above deadlock by moving memcg's hook to out of
mapping->tree_lock. charge/uncharge of pagecache/swapcache is protected
by page lock, not tree_lock.
After this patch, lock_page_cgroup() is not called under mapping->tree_lock.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
