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The user-settable knob, low_latency, has been the source of
several BUG reports which stem from flush_to_ldisc() running
in interrupt context. Since 3.12, which added several sleeping
locks (termios_rwsem and buf->lock) to the input processing path,
the frequency of these BUG reports has increased.
Note that changes in 3.12 did not introduce this regression;
sleeping locks were first added to the input processing path
with the removal of the BKL from N_TTY in commit
a88a69c91256418c5907c2f1f8a0ec0a36f9e6cc,
'n_tty: Fix loss of echoed characters and remove bkl from n_tty'
and later in commit 38db89799bdf11625a831c5af33938dcb11908b6,
'tty: throttling race fix'. Since those changes, executing
flush_to_ldisc() in interrupt_context (ie, low_latency set), is unsafe.
However, since most devices do not validate if the low_latency
setting is appropriate for the context (process or interrupt) in
which they receive data, some reports are due to misconfiguration.
Further, serial dma devices for which dma fails, resort to
interrupt receiving as a backup without resetting low_latency.
Historically, low_latency was used to force wake-up the reading
process rather than wait for the next scheduler tick. The
effect was to trim multiple milliseconds of latency from
when the process would receive new data.
Recent tests [1] have shown that the reading process now receives
data with only 10's of microseconds latency without low_latency set.
Remove the low_latency rx steering from tty_flip_buffer_push();
however, leave the knob as an optional hint to drivers that can
tune their rx fifos and such like. Cleanup stale code comments
regarding low_latency.
[1] https://lkml.org/lkml/2014/2/20/434
"Yay.. thats an annoying historical pain in the butt gone."
-- Alan Cox
Reported-by: Beat Bolli <bbolli@ewanet.ch>
Reported-by: Pavel Roskin <proski@gnu.org>
Acked-by: David Sterba <dsterba@suse.cz>
Cc: Grant Edwards <grant.b.edwards@gmail.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Hal Murray <murray+fedora@ip-64-139-1-69.sjc.megapath.net>
Cc: <stable@vger.kernel.org> # 3.12.x+
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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None of these files are actually using any __init type directives
and hence don't need to include <linux/init.h>. Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.
Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.
IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.
Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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One point is to have less places where we actually need tty pointer.
The other is that low_latency is bound to buffer processing and
buffers are now in tty_port. So it makes sense to move low_latency to
tty_port too.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.
tty_insert_flip_string this time.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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After commit "TTY: move tty buffers to tty_port", the tty buffers are
not freed in some drivers. This is because tty_port_destructor is not
called whenever a tty_port is freed. This was an assumption I counted
with but was unfortunately untrue. So fix the drivers to fulfil this
assumption.
To be sure, the TTY buffers (and later some stuff) are gone along with
the tty_port, we have to call tty_port_destroy at tear-down places.
This is mostly where the structure containing a tty_port is freed.
This patch does exactly that -- put tty_port_destroy at those places.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Currently we have no way to assign tty->port while performing tty
installation. There are two ways to provide the link tty_struct =>
tty_port. Either by calling tty_port_install from tty->ops->install or
tty_port_register_device called instead of tty_register_device when
the device is being set up after connected.
In this patch we modify most of the drivers to do the latter. When the
drivers use tty_register_device and we have tty_port already, we
switch to tty_port_register_device. So we have the tty_struct =>
tty_port link for free for those.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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It does not make the driver less racy though. Close and hangup should
be rewritten and tty refcounting used properly.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Acked-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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And use count from that.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Acked-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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There are two functions which only print a status. Let us do that
directly at places where they are called.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Acked-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Do not touch internal workqueue. Call tty_vhangup instead.
Note that finished hangup does not necessarily mean that all processes
are dead. Especially when the tty is a console. The code assumes that
right now.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Jiri Kosina <jkosina@suse.cz>
Acked-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Pull networking merge from David Miller:
"1) Move ixgbe driver over to purely page based buffering on receive.
From Alexander Duyck.
2) Add receive packet steering support to e1000e, from Bruce Allan.
3) Convert TCP MD5 support over to RCU, from Eric Dumazet.
4) Reduce cpu usage in handling out-of-order TCP packets on modern
systems, also from Eric Dumazet.
5) Support the IP{,V6}_UNICAST_IF socket options, making the wine
folks happy, from Erich Hoover.
6) Support VLAN trunking from guests in hyperv driver, from Haiyang
Zhang.
7) Support byte-queue-limtis in r8169, from Igor Maravic.
8) Outline code intended for IP_RECVTOS in IP_PKTOPTIONS existed but
was never properly implemented, Jiri Benc fixed that.
9) 64-bit statistics support in r8169 and 8139too, from Junchang Wang.
10) Support kernel side dump filtering by ctmark in netfilter
ctnetlink, from Pablo Neira Ayuso.
11) Support byte-queue-limits in gianfar driver, from Paul Gortmaker.
12) Add new peek socket options to assist with socket migration, from
Pavel Emelyanov.
13) Add sch_plug packet scheduler whose queue is controlled by
userland daemons using explicit freeze and release commands. From
Shriram Rajagopalan.
14) Fix FCOE checksum offload handling on transmit, from Yi Zou."
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1846 commits)
Fix pppol2tp getsockname()
Remove printk from rds_sendmsg
ipv6: fix incorrent ipv6 ipsec packet fragment
cpsw: Hook up default ndo_change_mtu.
net: qmi_wwan: fix build error due to cdc-wdm dependecy
netdev: driver: ethernet: Add TI CPSW driver
netdev: driver: ethernet: add cpsw address lookup engine support
phy: add am79c874 PHY support
mlx4_core: fix race on comm channel
bonding: send igmp report for its master
fs_enet: Add MPC5125 FEC support and PHY interface selection
net: bpf_jit: fix BPF_S_LDX_B_MSH compilation
net: update the usage of CHECKSUM_UNNECESSARY
fcoe: use CHECKSUM_UNNECESSARY instead of CHECKSUM_PARTIAL on tx
net: do not do gso for CHECKSUM_UNNECESSARY in netif_needs_gso
ixgbe: Fix issues with SR-IOV loopback when flow control is disabled
net/hyperv: Fix the code handling tx busy
ixgbe: fix namespace issues when FCoE/DCB is not enabled
rtlwifi: Remove unused ETH_ADDR_LEN defines
igbvf: Use ETH_ALEN
...
Fix up fairly trivial conflicts in drivers/isdn/gigaset/interface.c and
drivers/net/usb/{Kconfig,qmi_wwan.c} as per David.
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* do not test if tty->index is in bounds. It is always.
* tty->index is not a minor! Fix that.
>From now on, let's assume that the parameter of the function is tty
index with base being zero. This makes also the code more readable.
Factually, there is no real change as tty_driver->minor_start is zero,
so the tests are equivalent. But it did not make sense. And if this
had changed eventually, it would have caused troubles.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Cc: David Sterba <dsterba@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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All num, magic and owner are set by alloc_tty_driver. No need to
re-set them on each allocation site.
pti driver sets something different to what it passes to
alloc_tty_driver. It is not a bug, since we don't use the lines
parameter in any way. Anyway this is fixed, and now we do the right
thing.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Since all that include/linux/if_ppp.h does is #include <linux/ppp-ioctl.h>,
this replaces the occurrences of #include <linux/if_ppp.h> with
#include <linux/ppp-ioctl.h>.
It also corrects an error in Documentation/networking/l2tp.txt, where
it referenced include/linux/if_ppp.h as the source of some definitions
that are actually now defined in include/linux/if_pppol2tp.h.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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As planned by Arnd Bergmann, this moves the ipwireless driver to the
drivers/tty/ directory as that's where it really belongs.
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: David Sterba <dsterba@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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