The refcount is checked only in tty_unregister_ldisc and EBUSY returned
if it is nonzero. But none of the tty_unregister_ldisc callers act
anyhow if this (or any other) error is returned. So remove
tty_ldisc_ops::refcount completely and make tty_unregister_ldisc return
'void' in the next patches. That means we assume tty_unregister_ldisc is
not called while the ldisc might be in use. That relies on
try_module_get in get_ldops and module_put in put_ldops.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210505091928.22010-18-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Group the ctrl members under a single struct called ctrl. The new struct
contains 'pgrp', 'session', 'pktstatus', and 'packet'. 'pktstatus' and
'packet' used to be bits in a bitfield. The struct also contains the
lock protecting them to share the same cache line.
Note that commit c545b66c69 (tty: Serialize tcflow() with other tty
flow control changes) added a padding to the original bitfield. It was
for the bitfield to occupy a whole 64b word to avoid interferring stores
on Alpha (cannot we evaporate this arch with weird implications to C
code yet?). But it doesn't work as expected as the padding
(tty_struct::ctrl_unused) is aligned to a 8B boundary too and occupies
some bytes from the next word.
So make it reliable by:
1) setting __aligned of the struct -- that aligns the start, and
2) making 'unsigned long unused[0]' as the last member of the struct --
pads the end.
Add a kerneldoc comment for this grouped members.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
Link: https://lore.kernel.org/r/20210505091928.22010-14-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Group the flow flags under a single struct called flow. The new struct
contains 'stopped' and 'tco_stopped' bools which used to be bits in a
bitfield. The struct also contains the lock protecting them to
potentially share the same cache line.
Note that commit c545b66c69 (tty: Serialize tcflow() with other tty
flow control changes) added a padding to the original bitfield. It was
for the bitfield to occupy a whole 64b word to avoid interferring stores
on Alpha (cannot we evaporate this arch with weird implications to C
code yet?). But it doesn't work as expected as the padding
(tty_struct::unused) is aligned to a 8B boundary too and occupies some
bytes from the next word.
So make it reliable by:
1) setting __aligned of the struct -- that aligns the start, and
2) making 'unsigned long unused[0]' as the last member of the struct --
pads the end.
This is also the perfect time to start the documentation of tty_struct
where all this lives. So we start by documenting what these bools
actually serve for. And why we do all the alignment dances. Only the few
up-to-date information from the Theodore's comment made it into this new
Kerneldoc comment.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: "Maciej W. Rozycki" <macro@orcam.me.uk>
Link: https://lore.kernel.org/r/20210505091928.22010-13-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Handle !TTY_NORMAL as a short path and 'continue' the loop. Do the rest as
a normal code flow. This decreases the indentation level by one and
makes the code flow more understandable.
IOW, we avoid
if (cond) {
LONG CODE;
} else
single_line();
by
if (!cond) {
single_line();
continue;
}
LONG CODE;
While at it, invert also the 'if (!test_bit) A else B' into 'if
(test_bit) B else A'.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210505091928.22010-10-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move lnext handling from __receive_buf to n_tty_receive_buf_standard. It
simplifies the handling as it needs not fetching 'flag' and decrement
'count' in __receive_buf. Instead, all this is left up to the loop in
n_tty_receive_buf_standard which already does that.
This way, no need to repeat the action when n_tty_receive_char_special
returns true -- ldata->lnext is set there in that case, so the 'if
(ldata->lnext)' check is sufficient. The next patch will switch
n_tty_receive_char_special to return 'void'.
The result is much simplified code flow.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210505091928.22010-7-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
After the previous patches, n_tty_receive_buf_standard and
n_tty_receive_buf_fast differ only in handling of tty line and input
controls. Unlike n_tty_receive_buf_fast, n_tty_receive_buf_standard
handles them all (I_ISTRIP, I_IUCLC, L_IEXTEN, L_EXTPROC, and I_PARMRK).
So remove n_tty_receive_buf_fast and let n_tty_receive_buf_standard do
the handling. Actually most of the tests are only moved from
__receive_buf to n_tty_receive_buf_standard.
Again, the code duplication is not worth the theoretical speedup.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210505091928.22010-5-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
n_tty_receive_char_fast is a copy of n_tty_receive_char with one
exception: PARMRK is not doubled in the former. Unify these two and
double PARMRK depending on a newly added parameter (bool parmrk_dbl).
I don't think the theoretical speedup is worth the code duplication.
Which is directly connected with maintenance burden.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210505091928.22010-4-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The wrapper was meant as an optimization in commits eb3e4668bd (n_tty:
Un-inline slow-path n_tty_receive_char()) and e60d27c4d8 (n_tty:
Factor LNEXT processing from per-char i/o path). But the current
compiler (gcc 10) inlines it anyway (as expected). Actually, I'm not
sure it ever didn't. It would need to be marked with the noinline
attribute.
So remove this useless wrapper.
And if we ever introduce something similar, we need confirming numbers
first.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210505091928.22010-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Noone stepped up in the past two years since it was marked as BROKEN by
commit c7084edc3f (tty: mark Siemens R3964 line discipline as BROKEN).
Remove the line discipline for good.
Three remarks:
* we remove also the uapi header (as noone is able to use that interface
anyway)
* we do *not* remove the N_R3964 constant definition from tty.h, so it
remains reserved.
* in_interrupt() check is now removed from vt's con_put_char. Noone else
calls tty_operations::put_char from interrupt context.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210505091928.22010-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Our SoC's have always had a NS16650A UART core and older SoC's would
have a compatible string of: 'compatible = ""ns16550a"' and use the
8250_of driver. Our newer SoC's have added enhancements to the base
core to add support for DMA and accurate high speed baud rates and use
this newer 8250_bcm7271 driver. The Device Tree node for our enhanced
UARTs has a compatible string of: 'compatible = "brcm,bcm7271-uart",
"ns16550a"''. With both drivers running and the link order setup so
that the 8250_bcm7217 driver is initialized before the 8250_of driver,
we should bind the 8250_bcm7271 driver to the enhanced UART, or for
upstream kernels that don't have the 8250_bcm7271 driver, we bind to
the 8250_of driver.
The problem is that when both the 8250_of and 8250_bcm7271 drivers
were running, occasionally the 8250_of driver would be bound to the
enhanced UART instead of the 8250_bcm7271 driver. This was happening
because we use SCMI based clocks which come up late in initialization
and cause probe DEFER's when the two drivers get their clocks.
Occasionally the SCMI clock would become ready between the 8250_bcm7271
probe and the 8250_of probe and the 8250_of driver would be bound. To
fix this we decided to config only our 8250_bcm7271 driver and added
"ns16665a0" to the compatible string so the driver would work on our
older system.
This commit has of_platform_serial_probe() check specifically for the
"brcm,bcm7271-uart" and whether its companion driver is enabled. If it
is the case, and the clock provider is not ready, we want to make sure
that when the 8250_bcm7271.c driver returns EPROBE_DEFER, we are not
getting the UART registered via 8250_of.c.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20210423183206.3917725-1-f.fainelli@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
