History log of /linux-6.15/drivers/tty/tty_buffer.c (Results 1 – 25 of 112)
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Revision tags: v6.15, v6.15-rc7, v6.15-rc6, v6.15-rc5, v6.15-rc4, v6.15-rc3, v6.15-rc2, v6.15-rc1, v6.14, v6.14-rc7, v6.14-rc6, v6.14-rc5, v6.14-rc4, v6.14-rc3, v6.14-rc2, v6.14-rc1, v6.13, v6.13-rc7, v6.13-rc6, v6.13-rc5, v6.13-rc4, v6.13-rc3, v6.13-rc2, v6.13-rc1, v6.12, v6.12-rc7, v6.12-rc6, v6.12-rc5, v6.12-rc4, v6.12-rc3, v6.12-rc2, v6.12-rc1, v6.11, v6.11-rc7, v6.11-rc6, v6.11-rc5, v6.11-rc4, v6.11-rc3, v6.11-rc2, v6.11-rc1, v6.10, v6.10-rc7, v6.10-rc6, v6.10-rc5, v6.10-rc4, v6.10-rc3, v6.10-rc2, v6.10-rc1, v6.9, v6.9-rc7, v6.9-rc6, v6.9-rc5, v6.9-rc4, v6.9-rc3, v6.9-rc2, v6.9-rc1, v6.8, v6.8-rc7, v6.8-rc6, v6.8-rc5
# 548fcf03 15-Feb-2024 Ilpo Järvinen <[email protected]>

tty: Don't include tty_buffer.h in tty.h

There's no need to include linux/tty_buffer.h in linux/tty.h.
Move the include into tty_buffer.c that is actually using it.

Signed-off-by: Ilpo Järvinen <il

tty: Don't include tty_buffer.h in tty.h

There's no need to include linux/tty_buffer.h in linux/tty.h.
Move the include into tty_buffer.c that is actually using it.

Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


Revision tags: v6.8-rc4, v6.8-rc3, v6.8-rc2, v6.8-rc1, v6.7, v6.7-rc8, v6.7-rc7, v6.7-rc6, v6.7-rc5, v6.7-rc4, v6.7-rc3, v6.7-rc2, v6.7-rc1, v6.6, v6.6-rc7, v6.6-rc6, v6.6-rc5, v6.6-rc4, v6.6-rc3
# 083cfcf3 19-Sep-2023 Jiri Slaby (SUSE) <[email protected]>

tty: tty_buffer: use bool for 'restart' in tty_buffer_unlock_exclusive()

It's a boolean value, so no need for 'int' there.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lo

tty: tty_buffer: use bool for 'restart' in tty_buffer_unlock_exclusive()

It's a boolean value, so no need for 'int' there.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


Revision tags: v6.6-rc2, v6.6-rc1, v6.5, v6.5-rc7
# ebee41c8 16-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: tty_buffer: invert conditions in __tty_buffer_request_room()

We are used to handle "bad" states in the 'if's in the kernel. Refactor
(invert the two conditions in) __tty_buffer_request_room(),

tty: tty_buffer: invert conditions in __tty_buffer_request_room()

We are used to handle "bad" states in the 'if's in the kernel. Refactor
(invert the two conditions in) __tty_buffer_request_room(), so that the
code returns from the fast paths immediately instead of postponing to
the heavy end of the function.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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# 035197c9 16-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: tty_buffer: initialize variables in initializers already

It makes the code both more compact, and more understandable.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://l

tty: tty_buffer: initialize variables in initializers already

It makes the code both more compact, and more understandable.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


# 64365743 16-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: tty_buffer: better types in __tty_buffer_request_room()

* use bool for 'change' as it holds a result of a boolean.
* use size_t for 'left', so it is the same as 'size' which it is
compared to

tty: tty_buffer: better types in __tty_buffer_request_room()

* use bool for 'change' as it holds a result of a boolean.
* use size_t for 'left', so it is the same as 'size' which it is
compared to. Both are supposed to contain an unsigned value.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


# b49a0ff7 16-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: tty_buffer: use __tty_insert_flip_string_flags() in tty_insert_flip_char()

Use __tty_insert_flip_string_flags() for the slow path of
tty_insert_flip_char(). The former is generic enough, so the

tty: tty_buffer: use __tty_insert_flip_string_flags() in tty_insert_flip_char()

Use __tty_insert_flip_string_flags() for the slow path of
tty_insert_flip_char(). The former is generic enough, so there is no
reason to reimplement the injection once again.

So now we have a single function stuffing into tty buffers.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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# 2ce2983c 16-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: tty_buffer: let tty_prepare_flip_string() return size_t

The same as in the previous patch, tty_prepare_flip_string() accepts
size_t as an size argument. It returns the same size (or less). It i

tty: tty_buffer: let tty_prepare_flip_string() return size_t

The same as in the previous patch, tty_prepare_flip_string() accepts
size_t as an size argument. It returns the same size (or less). It is
unexpected that it returns a signed value and can confuse users to check
for negative values.

Instead, return the same size_t as accepted to make clear we return
values >= 0, where zero in fact means failure.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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# 6144922e 16-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: tty_buffer: switch insert functions to size_t

All the functions accept size_t as a size argument. They finally return
the same size (or less). It is quite unexpected that they return a
signed v

tty: tty_buffer: switch insert functions to size_t

All the functions accept size_t as a size argument. They finally return
the same size (or less). It is quite unexpected that they return a
signed value and can confuse users to check for negative values.

Instead, return the same size_t as accepted to make clear we return
values >= 0, where zero in fact means failure.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


# 4a8d99a4 16-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: tty_buffer: warn if losing flags in __tty_insert_flip_string_flags()

And add a WARN_ON_ONCE(need_flags) to make sure we are not losing flags
in __tty_insert_flip_string_flags().

Signed-off-by:

tty: tty_buffer: warn if losing flags in __tty_insert_flip_string_flags()

And add a WARN_ON_ONCE(need_flags) to make sure we are not losing flags
in __tty_insert_flip_string_flags().

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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# c26405fd 16-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: tty_buffer: unify tty_insert_flip_string_{fixed_flag,flags}()

They both do the same except for flags. One mem-copies the flags from
the caller, the other mem-sets to one flag given by the calle

tty: tty_buffer: unify tty_insert_flip_string_{fixed_flag,flags}()

They both do the same except for flags. One mem-copies the flags from
the caller, the other mem-sets to one flag given by the caller. This can
be unified with a simple if in the unified function.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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# 46bc78c8 16-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: tty_buffer: use struct_size() in tty_buffer_alloc()

Now, that tty_buffer::data has the right type, use struct_size() for
size calculation. struct_size() makes the code less error-prone and more

tty: tty_buffer: use struct_size() in tty_buffer_alloc()

Now, that tty_buffer::data has the right type, use struct_size() for
size calculation. struct_size() makes the code less error-prone and more
readable.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


Revision tags: v6.5-rc6
# 892bc209 10-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: use u8 for flags

This makes all those 'char's an explicit 'u8'. This is part of the
continuing unification of chars and flags to be consistent u8.

This approaches tty_port_default_receive_buf(

tty: use u8 for flags

This makes all those 'char's an explicit 'u8'. This is part of the
continuing unification of chars and flags to be consistent u8.

This approaches tty_port_default_receive_buf().

Note that we do not change signedness as we compile with
-funsigned-char.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Cc: William Hubbs <[email protected]>
Cc: Chris Brannon <[email protected]>
Cc: Kirk Reiser <[email protected]>
Cc: Samuel Thibault <[email protected]>
Cc: Marcel Holtmann <[email protected]>
Cc: Johan Hedberg <[email protected]>
Cc: Luiz Augusto von Dentz <[email protected]>
Cc: Dmitry Torokhov <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: Max Staudt <[email protected]>
Cc: Wolfgang Grandegger <[email protected]>
Cc: Marc Kleine-Budde <[email protected]>
Cc: Dario Binacchi <[email protected]>
Cc: Andreas Koensgen <[email protected]>
Cc: Jeremy Kerr <[email protected]>
Cc: Matt Johnston <[email protected]>
Cc: Krzysztof Kozlowski <[email protected]>
Cc: Liam Girdwood <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Jaroslav Kysela <[email protected]>
Cc: Takashi Iwai <[email protected]>
Acked-by: Mark Brown <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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# a8d9cd23 10-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: use u8 for chars

This makes all those 'unsigned char's an explicit 'u8'. This is part of
the continuing unification of chars and flags to be consistent u8.

This approaches tty_port_default_rec

tty: use u8 for chars

This makes all those 'unsigned char's an explicit 'u8'. This is part of
the continuing unification of chars and flags to be consistent u8.

This approaches tty_port_default_receive_buf(). Flags to be next.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Cc: William Hubbs <[email protected]>
Cc: Chris Brannon <[email protected]>
Cc: Kirk Reiser <[email protected]>
Cc: Samuel Thibault <[email protected]>
Cc: Dmitry Torokhov <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Max Staudt <[email protected]>
Cc: Wolfgang Grandegger <[email protected]>
Cc: Marc Kleine-Budde <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: Dario Binacchi <[email protected]>
Cc: Andreas Koensgen <[email protected]>
Cc: Jeremy Kerr <[email protected]>
Cc: Matt Johnston <[email protected]>
Cc: Liam Girdwood <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Jaroslav Kysela <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: Peter Ujfalusi <[email protected]>
Acked-by: Mark Brown <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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# 8d9526f9 10-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: switch count in tty_ldisc_receive_buf() to size_t

It comes from both paste_selection() and tty_port_default_receive_buf()
as unsigned (int and size_t respectively). Switch to size_t to converge

tty: switch count in tty_ldisc_receive_buf() to size_t

It comes from both paste_selection() and tty_port_default_receive_buf()
as unsigned (int and size_t respectively). Switch to size_t to converge
to that eventually.

Return the count as size_t too (the two callers above expect that).

Switch paste_selection()'s type of 'count' too, so that the returned and
passed type match.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


# 201560af 10-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: switch receive_buf() counts to size_t

'size_t' is what receive_buf() expects and returns while handling count.
So switch to 'size_t'.

This renders both local 'count' and 'rcvd' in flush_to_ldi

tty: switch receive_buf() counts to size_t

'size_t' is what receive_buf() expects and returns while handling count.
So switch to 'size_t'.

This renders both local 'count' and 'rcvd' in flush_to_ldisc() to be
size_t too.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


# 0b7a2b28 10-Aug-2023 Jiri Slaby (SUSE) <[email protected]>

tty: make tty_port_client_operations operate with u8

The parameters are already unsigned chars. So make them explicitly u8s,
as the rest is going to be unified to u8 eventually too.

Signed-off-by:

tty: make tty_port_client_operations operate with u8

The parameters are already unsigned chars. So make them explicitly u8s,
as the rest is going to be unified to u8 eventually too.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Cc: Rob Herring <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


Revision tags: v6.5-rc5, v6.5-rc4, v6.5-rc3, v6.5-rc2, v6.5-rc1, v6.4, v6.4-rc7, v6.4-rc6, v6.4-rc5, v6.4-rc4, v6.4-rc3, v6.4-rc2, v6.4-rc1, v6.3, v6.3-rc7, v6.3-rc6, v6.3-rc5, v6.3-rc4, v6.3-rc3, v6.3-rc2, v6.3-rc1, v6.2, v6.2-rc8, v6.2-rc7, v6.2-rc6, v6.2-rc5, v6.2-rc4, v6.2-rc3, v6.2-rc2, v6.2-rc1, v6.1, v6.1-rc8, v6.1-rc7, v6.1-rc6, v6.1-rc5, v6.1-rc4, v6.1-rc3, v6.1-rc2
# 2e2b4b89 19-Oct-2022 Ilpo Järvinen <[email protected]>

tty: Convert tty_buffer flags to bool

The struct tty_buffer has flags which is only used for storing TTYB_NORMAL.
There is also a few quite confusing operations for checking the presense
of TTYB_NOR

tty: Convert tty_buffer flags to bool

The struct tty_buffer has flags which is only used for storing TTYB_NORMAL.
There is also a few quite confusing operations for checking the presense
of TTYB_NORMAL. Simplify things by converting flags to bool.

Despite the name remaining the same, the meaning of "flags" is altered
slightly by this change. Previously it referred to flags of the buffer
(only TTYB_NORMAL being used as a flag). After this change, flags tell
whether the buffer contains/should be allocated with flags array along
with character data array. It is much more suitable name that
TTYB_NORMAL was for this purpose, thus the name remains.

Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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# 15730dc4 19-Oct-2022 Ilpo Järvinen <[email protected]>

tty: Cleanup tty buffer align mask

Don't use decimal for mask. Don't use literal for aligning.

Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/202210191

tty: Cleanup tty buffer align mask

Don't use decimal for mask. Don't use literal for aligning.

Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


Revision tags: v6.1-rc1, v6.0, v6.0-rc7, v6.0-rc6, v6.0-rc5, v6.0-rc4, v6.0-rc3, v6.0-rc2
# 56c14fb4 18-Aug-2022 Vincent Whitchurch <[email protected]>

tty: Fix lookahead_buf crash with serdev

Do not follow a NULL pointer if the tty_port_client_operations does not
implement the ->lookahead_buf() callback, which is the case with
serdev's ttyport.

R

tty: Fix lookahead_buf crash with serdev

Do not follow a NULL pointer if the tty_port_client_operations does not
implement the ->lookahead_buf() callback, which is the case with
serdev's ttyport.

Reported-by: Hans de Goede <[email protected]>
Fixes: 6bb6fa6908ebd3 ("tty: Implement lookahead to process XON/XOFF timely")
Reviewed-by: Ilpo Järvinen <[email protected]>
Signed-off-by: Vincent Whitchurch <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


Revision tags: v6.0-rc1, v5.19, v5.19-rc8, v5.19-rc7, v5.19-rc6
# a501ab75 07-Jul-2022 Jiri Slaby <[email protected]>

tty: use new tty_insert_flip_string_and_push_buffer() in pty_write()

There is a race in pty_write(). pty_write() can be called in parallel
with e.g. ioctl(TIOCSTI) or ioctl(TCXONC) which also insert

tty: use new tty_insert_flip_string_and_push_buffer() in pty_write()

There is a race in pty_write(). pty_write() can be called in parallel
with e.g. ioctl(TIOCSTI) or ioctl(TCXONC) which also inserts chars to
the buffer. Provided, tty_flip_buffer_push() in pty_write() is called
outside the lock, it can commit inconsistent tail. This can lead to out
of bounds writes and other issues. See the Link below.

To fix this, we have to introduce a new helper called
tty_insert_flip_string_and_push_buffer(). It does both
tty_insert_flip_string() and tty_flip_buffer_commit() under the port
lock. It also calls queue_work(), but outside the lock. See
71a174b39f10 (pty: do tty_flip_buffer_push without port->lock in
pty_write) for the reasons.

Keep the helper internal-only (in drivers' tty.h). It is not intended to
be used widely.

Link: https://seclists.org/oss-sec/2022/q2/155
Fixes: 71a174b39f10 (pty: do tty_flip_buffer_push without port->lock in pty_write)
Cc: 一只狗 <[email protected]>
Cc: Dan Carpenter <[email protected]>
Suggested-by: Hillf Danton <[email protected]>
Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


# 716b1058 07-Jul-2022 Jiri Slaby <[email protected]>

tty: extract tty_flip_buffer_commit() from tty_flip_buffer_push()

We will need this new helper in the next patch.

Cc: Hillf Danton <[email protected]>
Cc: 一只狗 <[email protected]>
Cc: Dan Carpente

tty: extract tty_flip_buffer_commit() from tty_flip_buffer_push()

We will need this new helper in the next patch.

Cc: Hillf Danton <[email protected]>
Cc: 一只狗 <[email protected]>
Cc: Dan Carpenter <[email protected]>
Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


Revision tags: v5.19-rc5, v5.19-rc4, v5.19-rc3, v5.19-rc2
# 6bb6fa69 06-Jun-2022 Ilpo Järvinen <[email protected]>

tty: Implement lookahead to process XON/XOFF timely

When tty is not read from, XON/XOFF may get stuck into an
intermediate buffer. As those characters are there to do software
flow-control, it is no

tty: Implement lookahead to process XON/XOFF timely

When tty is not read from, XON/XOFF may get stuck into an
intermediate buffer. As those characters are there to do software
flow-control, it is not very useful. In the case where neither end
reads from ttys, the receiving ends might not be able receive the
XOFF characters and just keep sending more data to the opposite
direction. This problem is almost guaranteed to occur with DMA
which sends data in large chunks.

If TTY is slow to process characters, that is, eats less than given
amount in receive_buf, invoke lookahead for the rest of the chars
to process potential XON/XOFF characters.

We need to keep track of how many characters have been processed by the
lookahead to avoid processing the flow control char again on the normal
path. Bookkeeping occurs parallel on two layers (tty_buffer and n_tty)
to avoid passing the lookahead_count through the whole call chain.

When a flow-control char is processed, two things must occur:
a) it must not be treated as normal char
b) if not yet processed, flow-control actions need to be taken
The return value of n_tty_receive_char_flow_ctrl() tells caller a), and
b) is kept internal to n_tty_receive_char_flow_ctrl().

If characters were previous looked ahead, __receive_buf() makes two
calls to the appropriate n_tty_receive_buf_* function. First call is
made with lookahead_done=true for the characters that were subject to
lookahead earlier and then with lookahead=false for the new characters.
Either of the calls might be skipped when it has no characters to
handle.

Reported-by: Gilles Buloz <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


Revision tags: v5.19-rc1, v5.18, v5.18-rc7
# 6b9dbedb 13-May-2022 Qi Zheng <[email protected]>

tty: fix deadlock caused by calling printk() under tty_port->lock

pty_write() invokes kmalloc() which may invoke a normal printk() to print
failure message. This can cause a deadlock in the scenari

tty: fix deadlock caused by calling printk() under tty_port->lock

pty_write() invokes kmalloc() which may invoke a normal printk() to print
failure message. This can cause a deadlock in the scenario reported by
syz-bot below:

CPU0 CPU1 CPU2
---- ---- ----
lock(console_owner);
lock(&port_lock_key);
lock(&port->lock);
lock(&port_lock_key);
lock(&port->lock);
lock(console_owner);

As commit dbdda842fe96 ("printk: Add console owner and waiter logic to
load balance console writes") said, such deadlock can be prevented by
using printk_deferred() in kmalloc() (which is invoked in the section
guarded by the port->lock). But there are too many printk() on the
kmalloc() path, and kmalloc() can be called from anywhere, so changing
printk() to printk_deferred() is too complicated and inelegant.

Therefore, this patch chooses to specify __GFP_NOWARN to kmalloc(), so
that printk() will not be called, and this deadlock problem can be
avoided.

Syzbot reported the following lockdep error:

======================================================
WARNING: possible circular locking dependency detected
5.4.143-00237-g08ccc19a-dirty #10 Not tainted
------------------------------------------------------
syz-executor.4/29420 is trying to acquire lock:
ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1752 [inline]
ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: vprintk_emit+0x2ca/0x470 kernel/printk/printk.c:2023

but task is already holding lock:
ffff8880119c9158 (&port->lock){-.-.}-{2:2}, at: pty_write+0xf4/0x1f0 drivers/tty/pty.c:120

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (&port->lock){-.-.}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159
tty_port_tty_get drivers/tty/tty_port.c:288 [inline] <-- lock(&port->lock);
tty_port_default_wakeup+0x1d/0xb0 drivers/tty/tty_port.c:47
serial8250_tx_chars+0x530/0xa80 drivers/tty/serial/8250/8250_port.c:1767
serial8250_handle_irq.part.0+0x31f/0x3d0 drivers/tty/serial/8250/8250_port.c:1854
serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1827 [inline] <-- lock(&port_lock_key);
serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1870
serial8250_interrupt+0xfd/0x200 drivers/tty/serial/8250/8250_core.c:126
__handle_irq_event_percpu+0x109/0xa50 kernel/irq/handle.c:156
[...]

-> #1 (&port_lock_key){-.-.}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159
serial8250_console_write+0x184/0xa40 drivers/tty/serial/8250/8250_port.c:3198
<-- lock(&port_lock_key);
call_console_drivers kernel/printk/printk.c:1819 [inline]
console_unlock+0x8cb/0xd00 kernel/printk/printk.c:2504
vprintk_emit+0x1b5/0x470 kernel/printk/printk.c:2024 <-- lock(console_owner);
vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394
printk+0xba/0xed kernel/printk/printk.c:2084
register_console+0x8b3/0xc10 kernel/printk/printk.c:2829
univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:681
console_init+0x49d/0x6d3 kernel/printk/printk.c:2915
start_kernel+0x5e9/0x879 init/main.c:713
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241

-> #0 (console_owner){....}-{0:0}:
[...]
lock_acquire+0x127/0x340 kernel/locking/lockdep.c:4734
console_trylock_spinning kernel/printk/printk.c:1773 [inline] <-- lock(console_owner);
vprintk_emit+0x307/0x470 kernel/printk/printk.c:2023
vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394
printk+0xba/0xed kernel/printk/printk.c:2084
fail_dump lib/fault-inject.c:45 [inline]
should_fail+0x67b/0x7c0 lib/fault-inject.c:144
__should_failslab+0x152/0x1c0 mm/failslab.c:33
should_failslab+0x5/0x10 mm/slab_common.c:1224
slab_pre_alloc_hook mm/slab.h:468 [inline]
slab_alloc_node mm/slub.c:2723 [inline]
slab_alloc mm/slub.c:2807 [inline]
__kmalloc+0x72/0x300 mm/slub.c:3871
kmalloc include/linux/slab.h:582 [inline]
tty_buffer_alloc+0x23f/0x2a0 drivers/tty/tty_buffer.c:175
__tty_buffer_request_room+0x156/0x2a0 drivers/tty/tty_buffer.c:273
tty_insert_flip_string_fixed_flag+0x93/0x250 drivers/tty/tty_buffer.c:318
tty_insert_flip_string include/linux/tty_flip.h:37 [inline]
pty_write+0x126/0x1f0 drivers/tty/pty.c:122 <-- lock(&port->lock);
n_tty_write+0xa7a/0xfc0 drivers/tty/n_tty.c:2356
do_tty_write drivers/tty/tty_io.c:961 [inline]
tty_write+0x512/0x930 drivers/tty/tty_io.c:1045
__vfs_write+0x76/0x100 fs/read_write.c:494
[...]

other info that might help us debug this:

Chain exists of:
console_owner --> &port_lock_key --> &port->lock

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: b6da31b2c07c ("tty: Fix data race in tty_insert_flip_string_fixed_flag")
Signed-off-by: Qi Zheng <[email protected]>
Acked-by: Jiri Slaby <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Cc: Akinobu Mita <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...


Revision tags: v5.18-rc6, v5.18-rc5, v5.18-rc4, v5.18-rc3, v5.18-rc2, v5.18-rc1, v5.17, v5.17-rc8, v5.17-rc7, v5.17-rc6, v5.17-rc5, v5.17-rc4, v5.17-rc3, v5.17-rc2, v5.17-rc1, v5.16, v5.16-rc8, v5.16-rc7, v5.16-rc6, v5.16-rc5, v5.16-rc4, v5.16-rc3
# bc17b723 26-Nov-2021 Jiri Slaby <[email protected]>

tty: reformat kernel-doc in tty_buffer.c

Kernel-doc is a bit strict about some formatting. So fix these:
1) When there is a tab in comments, it thinks the line is a continuation
one. So the descr

tty: reformat kernel-doc in tty_buffer.c

Kernel-doc is a bit strict about some formatting. So fix these:
1) When there is a tab in comments, it thinks the line is a continuation
one. So the description of the functions end up as descriptions of
the last parameter described. Remove the tabs.

2) Remove newlines before parameters description and after the comments.
This was not wrong per se, only inconsistent with the rest of the
file.

3) Add periods to the end of sentences where appropriate.

4) Add "()" to function names and "%" to constants, so that they are
properly highlighted.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


# 5db96ef2 22-Nov-2021 Jiri Slaby <[email protected]>

tty: drop tty_schedule_flip()

Since commit a9c3f68f3cd8d (tty: Fix low_latency BUG) in 2014,
tty_flip_buffer_push() is only a wrapper to tty_schedule_flip(). All
users were converted in the previous

tty: drop tty_schedule_flip()

Since commit a9c3f68f3cd8d (tty: Fix low_latency BUG) in 2014,
tty_flip_buffer_push() is only a wrapper to tty_schedule_flip(). All
users were converted in the previous patches, so remove
tty_schedule_flip() completely while inlining its body into
tty_flip_buffer_push().

One less exported function.

Reviewed-by: Johan Hovold <[email protected]>
Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...


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