If a USB-to-serial adapter is unplugged, the driver re-initializes, with
dev->hard_header_len and dev->addr_len set to zero, instead of the correct
values. If then a packet is sent through the half-dead interface, the
kernel will panic due to running out of headroom in the skb when pushing
for the AX.25 headers resulting in this panic:
[<c0595468>] (skb_panic) from [<c0401f70>] (skb_push+0x4c/0x50)
[<c0401f70>] (skb_push) from [<bf0bdad4>] (ax25_hard_header+0x34/0xf4 [ax25])
[<bf0bdad4>] (ax25_hard_header [ax25]) from [<bf0d05d4>] (ax_header+0x38/0x40 [mkiss])
[<bf0d05d4>] (ax_header [mkiss]) from [<c041b584>] (neigh_compat_output+0x8c/0xd8)
[<c041b584>] (neigh_compat_output) from [<c043e7a8>] (ip_finish_output+0x2a0/0x914)
[<c043e7a8>] (ip_finish_output) from [<c043f948>] (ip_output+0xd8/0xf0)
[<c043f948>] (ip_output) from [<c043f04c>] (ip_local_out_sk+0x44/0x48)
This patch makes mkiss behave like the 6pack driver. 6pack does not
panic. In 6pack.c sp_setup() (same function name here) the values for
dev->hard_header_len and dev->addr_len are set to the same values as in
my mkiss patch.
[ralf@linux-mips.org: Massages original submission to conform to the usual
standards for patch submissions.]
Signed-off-by: Thomas Osterried <thomas@osterried.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This was entirely automated, using the script by Al:
PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)
to do the replacement at the end of the merge window.
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
a trans_start struct member exists twice:
- in struct net_device (legacy)
- in struct netdev_queue
Instead of open-coding dev->trans_start usage to obtain the current
trans_start value, use dev_trans_start() instead.
This is not exactly the same, as dev_trans_start also considers
the trans_start values of the netdev queues owned by the device
and provides the most recent one.
For legacy devices this doesn't matter as dev_trans_start can cope
with netdev trans_start values of 0 (they are ignored).
This is a prerequisite to eventual removal of dev->trans_start.
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
commit d79f16c046 fixed a user triggerable
scribble on free memory but added a new one which allows the user to
scribble even more and user controlled data into freed space.
As with 6pack we need to halt the queue before we free the buffers, because
the transmit logic is not protected by the semaphore.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If register_netdev() fails we are not propagating the error and
we return success because ax_open() succeeded previously.
Fix this by checking the return value of ax_open() and
register_netdev() and propagate the error in case of failure.
Reported-by: RUC_Soft_Sec <zy900702@163.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We get a static checker warning here on devel kernels:
drivers/net/hamradio/mkiss.c:560 ax_xmit()
warn: variable dereferenced before check 'skb' (see line 532)
It turns out that the NULL check can be deleted.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Before the ax25 stack calls dev_queue_xmit it always calls
ax25_type_trans which sets skb->protocol to ETH_P_AX25.
Which means that by looking at the protocol type it is possible to
detect IP packets that have not been munged by the ax25 stack in
ndo_start_xmit and call a function to munge them.
Rename ax25_neigh_xmit to ax25_ip_xmit and tweak the return type and
value to be appropriate for an ndo_start_xmit function.
Update all of the ax25 devices to test the protocol type for ETH_P_IP
and return ax25_ip_xmit as the first thing they do. This preserves
the existing semantics of IP packet processing, but the timing will be
a little different as the IP packets now pass through the qdisc layer
before reaching the ax25 ip packet processing.
Remove the now unnecessary ax25 neighbour table operations.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
AX25 already has it's own private arp cache operations to isolate
it's abuse of dev_rebuild_header to transmit packets. Add a function
ax25_neigh_construct that will allow all of the ax25 devices to
force using these operations, so that the generic arp code does
not need to.
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-hams@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The two sets of header operations are functionally identical remove the
duplicate definition.
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-hams@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Several files refer to an old address for the Free Software Foundation
in the file header comment. Resolve by replacing the address with
the URL <http://www.gnu.org/licenses/> so that we do not have to keep
updating the header comments anytime the address changes.
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Veaceslav Falico <vfalico@redhat.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: Haiyang Zhang <haiyangz@microsoft.com>
CC: "K. Y. Srinivasan" <kys@microsoft.com>
CC: Paul Mackerras <paulus@samba.org>
CC: Ian Campbell <ian.campbell@citrix.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: "Michael S. Tsirkin" <mst@redhat.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Adding casts of objects to the same type is unnecessary
and confusing for a human reader.
For example, this cast:
int y;
int *p = (int *)&y;
I used the coccinelle script below to find and remove these
unnecessary casts. I manually removed the conversions this
script produces of casts with __force, __iomem and __user.
@@
type T;
T *p;
@@
- (T *)p
+ p
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Remove all #inclusions of asm/system.h preparatory to splitting and killing
it. Performed with the following command:
perl -p -i -e 's!^#\s*include\s*<asm/system[.]h>.*\n!!' `grep -Irl '^#\s*include\s*<asm/system[.]h>' *`
Signed-off-by: David Howells <dhowells@redhat.com>
Lockdep found a locking inconsistency in the mkiss_close function:
> kernel: [ INFO: inconsistent lock state ]
> kernel: 2.6.39.1 #3
> kernel: ---------------------------------
> kernel: inconsistent {IN-SOFTIRQ-R} -> {SOFTIRQ-ON-W} usage.
> kernel: ax25ipd/2813 [HC0[0]:SC0[0]:HE1:SE1] takes:
> kernel: (disc_data_lock){+++?.-}, at: [<ffffffffa018552b>] mkiss_close+0x1b/0x90 [mkiss]
> kernel: {IN-SOFTIRQ-R} state was registered at:
The message hints that disc_data_lock is aquired with softirqs disabled,
but does not itself disable softirqs, which can in rare circumstances
lead to a deadlock.
The same problem is present in the 6pack driver, this patch fixes both
by using write_lock_bh instead of write_lock.
Reported-by: Bernard F6BVP <f6bvp@free.fr>
Tested-by: Bernard F6BVP <f6bvp@free.fr>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Ralf Baechle<ralf@linux-mips.org>
Cc: stable@kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
This reverts commit b1c43f82c5.
It was broken in so many ways, and results in random odd pty issues.
It re-introduced the buggy schedule_work() in flush_to_ldisc() that can
cause endless work-loops (see commit a5660b41af6a: "tty: fix endless
work loop when the buffer fills up").
It also used an "unsigned int" return value fo the ->receive_buf()
function, but then made multiple functions return a negative error code,
and didn't actually check for the error in the caller.
And it didn't actually work at all. BenH bisected down odd tty behavior
to it:
"It looks like the patch is causing some major malfunctions of the X
server for me, possibly related to PTYs. For example, cat'ing a
large file in a gnome terminal hangs the kernel for -minutes- in a
loop of what looks like flush_to_ldisc/workqueue code, (some ftrace
data in the quoted bits further down).
...
Some more data: It -looks- like what happens is that the
flush_to_ldisc work queue entry constantly re-queues itself (because
the PTY is full ?) and the workqueue thread will basically loop
forver calling it without ever scheduling, thus starving the consumer
process that could have emptied the PTY."
which is pretty much exactly the problem we fixed in a5660b41af.
Milton Miller pointed out the 'unsigned int' issue.
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reported-by: Milton Miller <miltonm@bga.com>
Cc: Stefan Bigler <stefan.bigler@keymile.com>
Cc: Toby Gray <toby.gray@realvnc.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
it makes it simpler to keep track of the amount of
bytes received and simplifies how flush_to_ldisc counts
the remaining bytes. It also fixes a bug of lost bytes
on n_tty when flushing too many bytes via the USB
serial gadget driver.
Tested-by: Stefan Bigler <stefan.bigler@keymile.com>
Tested-by: Toby Gray <toby.gray@realvnc.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Get rid of init_MUTEX[_LOCKED]() and use sema_init() instead.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
Acked-by: David Miller <davem@davemloft.net>
LKML-Reference: <20100907125055.368389976@linutronix.de>
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
My last commit introduced an typo causing the
compat_ioctl function to do nothing useful.
The obvious way for an ioctl function to work
is to look at the command, not the argument first.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Slip and a few other drivers use the same ioctl numbers on
tty devices that are normally meant for sockets. This causes
problems with our compat_ioctl handling that tries to convert
the data structures in a different format.
Fortunately, these five drivers all use 32 bit compatible
data structures in the ioctl numbers, so we can just add
a trivial compat_ioctl conversion function to each of them.
SIOCSIFENCAP and SIOCGIFENCAP do not need to live in
fs/compat_ioctl.c after this any more, and they are not
used on any sockets.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This typo was introduced by 5793f4be23 on
October 14, 2005 ...
Reported-by: Matti Aarnio <matti.aarnio@zmailer.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch is the result of an automatic spatch transformation to convert
all ndo_start_xmit() return values of 0 to NETDEV_TX_OK.
Some occurences are missed by the automatic conversion, those will be
handled in a seperate patch.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Convert magic values 1 and -1 to NETDEV_TX_BUSY and NETDEV_TX_LOCKED respectively.
0 (NETDEV_TX_OK) is not changed to keep the noise down, except in very few cases
where its in direct proximity to one of the other values.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Impact: Use 'static const char[]' instead of 'static char[]' and while
being at it fix an issue in 'mkiss_init_driver', where in case of an
error the status code was not passed to printk.
Fix this warnings:
drivers/net/hamradio/6pack.c: In function 'sixpack_init_driver':
drivers/net/hamradio/6pack.c:802: warning: format not a string literal and no format arguments
drivers/net/hamradio/bpqether.c: In function 'bpq_init_driver':
drivers/net/hamradio/bpqether.c:609: warning: format not a string literal and no format arguments
drivers/net/hamradio/mkiss.c: In function 'mkiss_init_driver':
drivers/net/hamradio/mkiss.c:988: warning: format not a string literal and no format arguments
drivers/net/hamradio/mkiss.c:991: warning: format not a string literal and no format arguments
drivers/net/hamradio/scc.c: In function 'scc_init_driver':
drivers/net/hamradio/scc.c:2109: warning: format not a string literal and no format arguments
drivers/net/hamradio/yam.c: In function 'yam_init_driver':
drivers/net/hamradio/yam.c:1094: warning: format not a string literal and no format arguments
Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
In each case, if the NULL test is necessary, then the dereference should be
moved below the NULL test.
The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@@
type T;
expression E;
identifier i,fld;
statement S;
@@
- T i = E->fld;
+ T i;
... when != E
when != i
if (E == NULL) S
+ i = E->fld;
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>
The generic packet receive code takes care of setting
netdev->last_rx when necessary, for the sake of the
bonding ARP monitor.
Drivers need not do it any more.
Some cases had to be skipped over because the drivers
were making use of the ->last_rx value themselves.
Signed-off-by: David S. Miller <davem@davemloft.net>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (1232 commits)
iucv: Fix bad merging.
net_sched: Add size table for qdiscs
net_sched: Add accessor function for packet length for qdiscs
net_sched: Add qdisc_enqueue wrapper
highmem: Export totalhigh_pages.
ipv6 mcast: Omit redundant address family checks in ip6_mc_source().
net: Use standard structures for generic socket address structures.
ipv6 netns: Make several "global" sysctl variables namespace aware.
netns: Use net_eq() to compare net-namespaces for optimization.
ipv6: remove unused macros from net/ipv6.h
ipv6: remove unused parameter from ip6_ra_control
tcp: fix kernel panic with listening_get_next
tcp: Remove redundant checks when setting eff_sacks
tcp: options clean up
tcp: Fix MD5 signatures for non-linear skbs
sctp: Update sctp global memory limit allocations.
sctp: remove unnecessary byteshifting, calculate directly in big-endian
sctp: Allow only 1 listening socket with SO_REUSEADDR
sctp: Do not leak memory on multiple listen() calls
sctp: Support ipv6only AF_INET6 sockets.
...
Move the line disciplines towards a conventional ->ops arrangement. For
the moment the actual 'tty_ldisc' struct in the tty is kept as part of
the tty struct but this can then be changed if it turns out that when it
all settles down we want to refcount ldiscs separately to the tty.
Pull the ldisc code out of /proc and put it with our ldisc code.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add netif_addr_{lock,unlock}{,_bh}() helpers.
Use them to protect operations that operate on or read
the network device unicast and multicast address lists.
Also use them in cases where the code simply wants to
block calls into the driver's ->set_rx_mode() and
->set_multicast_list() methods.
Signed-off-by: David S. Miller <davem@davemloft.net>
Something Arjan suggested which allows us to clean up the code nicely
Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Operations are now a shared const function block as with most other Linux
objects
- Introduce wrappers for some optional functions to get consistent behaviour
- Wrap put_char which used to be patched by the tty layer
- Document which functions are needed/optional
- Make put_char report success/fail
- Cache the driver->ops pointer in the tty as tty->ops
- Remove various surplus lock calls we no longer need
- Remove proc_write method as noted by Alexey Dobriyan
- Introduce some missing sanity checks where certain driver/ldisc
combinations would oops as they didn't check needed methods were present
[akpm@linux-foundation.org: fix fs/compat_ioctl.c build]
[akpm@linux-foundation.org: fix isicom]
[akpm@linux-foundation.org: fix arch/ia64/hp/sim/simserial.c build]
[akpm@linux-foundation.org: fix kgdb]
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
According to one of OOPSes reported by Jann softirq can break
while skb is prepared for netif_rx. The report isn't complete,
so the real reason of the later bug could be different, but
IMHO this locking break in ax_bump is unsafe and unnecessary.
Reported-and-tested-by: Jann Traschewski <jann@gmx.de>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Since hardware header operations are part of the protocol class
not the device instance, make them into a separate object and
save memory.
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Only the callsign but not the SSID part of an AX.25 address is ASCII
based but Linux by initializes the SSID which should be just a 4-bit
number from ASCII anyway.
Fix that and convert the code to use a shared constant for both default
addresses. While at it, use the same style for null_ax25_address also.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Various drivers use xmit_lock internally to synchronise with their
transmission routines. They do so without setting xmit_lock_owner.
This is fine as long as netpoll is not in use.
With netpoll it is possible for deadlocks to occur if xmit_lock_owner
isn't set. This is because if a printk occurs while xmit_lock is held
and xmit_lock_owner is not set can cause netpoll to attempt to take
xmit_lock recursively.
While it is possible to resolve this by getting netpoll to use
trylock, it is suboptimal because netpoll's sole objective is to
maximise the chance of getting the printk out on the wire. So
delaying or dropping the message is to be avoided as much as possible.
So the only alternative is to always set xmit_lock_owner. The
following patch does this by introducing the netif_tx_lock family of
functions that take care of setting/unsetting xmit_lock_owner.
I renamed xmit_lock to _xmit_lock to indicate that it should not be
used directly. I didn't provide irq versions of the netif_tx_lock
functions since xmit_lock is meant to be a BH-disabling lock.
This is pretty much a straight text substitution except for a small
bug fix in winbond. It currently uses
netif_stop_queue/spin_unlock_wait to stop transmission. This is
unsafe as an IRQ can potentially wake up the queue. So it is safer to
use netif_tx_disable.
The hamradio bits used spin_lock_irq but it is unnecessary as
xmit_lock must never be taken in an IRQ handler.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
MODULE_PARM was actually breaking: recent gcc version optimize them out as
unused. It's time to replace the last users, which are generally in the
most unloved drivers anyway.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The API and code have been through various bits of initial review by
serial driver people but they definitely need to live somewhere for a
while so the unconverted drivers can get knocked into shape, existing
drivers that have been updated can be better tuned and bugs whacked out.
This replaces the tty flip buffers with kmalloc objects in rings. In the
normal situation for an IRQ driven serial port at typical speeds the
behaviour is pretty much the same, two buffers end up allocated and the
kernel cycles between them as before.
When there are delays or at high speed we now behave far better as the
buffer pool can grow a bit rather than lose characters. This also means
that we can operate at higher speeds reliably.
For drivers that receive characters in blocks (DMA based, USB and
especially virtualisation) the layer allows a lot of driver specific
code that works around the tty layer with private secondary queues to be
removed. The IBM folks need this sort of layer, the smart serial port
people do, the virtualisers do (because a virtualised tty typically
operates at infinite speed rather than emulating 9600 baud).
Finally many drivers had invalid and unsafe attempts to avoid buffer
overflows by directly invoking tty methods extracted out of the innards
of work queue structs. These are no longer needed and all go away. That
fixes various random hangs with serial ports on overflow.
The other change in here is to optimise the receive_room path that is
used by some callers. It turns out that only one ldisc uses receive room
except asa constant and it updates it far far less than the value is
read. We thus make it a variable not a function call.
I expect the code to contain bugs due to the size alone but I'll be
watching and squashing them and feeding out new patches as it goes.
Because the buffers now dynamically expand you should only run out of
buffering when the kernel runs out of memory for real. That means a lot of
the horrible hacks high performance drivers used to do just aren't needed any
more.
Description:
tty_insert_flip_char is an old API and continues to work as before, as does
tty_flip_buffer_push() [this is why many drivers dont need modification]. It
does now also return the number of chars inserted
There are also
tty_buffer_request_room(tty, len)
which asks for a buffer block of the length requested and returns the space
found. This improves efficiency with hardware that knows how much to
transfer.
and tty_insert_flip_string_flags(tty, str, flags, len)
to insert a string of characters and flags
For a smart interface the usual code is
len = tty_request_buffer_room(tty, amount_hardware_says);
tty_insert_flip_string(tty, buffer_from_card, len);
More description!
At the moment tty buffers are attached directly to the tty. This is causing a
lot of the problems related to tty layer locking, also problems at high speed
and also with bursty data (such as occurs in virtualised environments)
I'm working on ripping out the flip buffers and replacing them with a pool of
dynamically allocated buffers. This allows both for old style "byte I/O"
devices and also helps virtualisation and smart devices where large blocks of
data suddenely materialise and need storing.
So far so good. Lots of drivers reference tty->flip.*. Several of them also
call directly and unsafely into function pointers it provides. This will all
break. Most drivers can use tty_insert_flip_char which can be kept as an API
but others need more.
At the moment I've added the following interfaces, if people think more will
be needed now is a good time to say
int tty_buffer_request_room(tty, size)
Try and ensure at least size bytes are available, returns actual room (may be
zero). At the moment it just uses the flipbuf space but that will change.
Repeated calls without characters being added are not cumulative. (ie if you
call it with 1, 1, 1, and then 4 you'll have four characters of space. The
other functions will also try and grow buffers in future but this will be a
more efficient way when you know block sizes.
int tty_insert_flip_char(tty, ch, flag)
As before insert a character if there is room. Now returns 1 for success, 0
for failure.
int tty_insert_flip_string(tty, str, len)
Insert a block of non error characters. Returns the number inserted.
int tty_prepare_flip_string(tty, strptr, len)
Adjust the buffer to allow len characters to be added. Returns a buffer
pointer in strptr and the length available. This allows for hardware that
needs to use functions like insl or mencpy_fromio.
Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
With the previous missing-unlock fix the spinlock is dropped only
after the tty->driver->write() call which might sleep.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The unlocking disappeared during commit
5793f4be23.
Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Ralf Baechle
Linus Torvalds
Florian Westphal
Alan
David Miller
Fabio Estevam
Dan Carpenter
Eric W. Biederman
Tom Gundersen
Jeff Kirsher
Andi Kleen
Joe Perches
David Howells
Arnd Bergmann
Felipe Balbi
Thomas Gleixner
Tejun Heo
Stephen Hemminger
Patrick McHardy
Hannes Eder
Stephen Hemminger
Julia Lawall
Eugene Teo
Alan Cox
Alan Cox
Jarek Poplawski
Al Viro
Al Viro
Jörn Engel
Herbert Xu
Rusty Russell
Francois Romieu
Jesper Juhl