/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Copyright 2014-2015 Analog Devices Inc.
 *  Author: Lars-Peter Clausen <lars@metafoo.de>
 */

#ifndef __IIO_DMAENGINE_H__
#define __IIO_DMAENGINE_H__

struct iio_buffer;
struct device;

struct iio_buffer *iio_dmaengine_buffer_alloc(struct device *dev,
	const char *channel);
void iio_dmaengine_buffer_free(struct iio_buffer *buffer);

#endif
s Anderson</name>
<email>dianders@chromium.org</email>
</author>
<published>2023-08-04T14:00:42Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=8d539b84f1e3478436f978ceaf55a0b6cab497b5'/>
<id>urn:sha1:8d539b84f1e3478436f978ceaf55a0b6cab497b5</id>
<content type='text'>
The APIs that allow backtracing across CPUs have always had a way to
exclude the current CPU.  This convenience means callers didn't need to
find a place to allocate a CPU mask just to handle the common case.

Let's extend the API to take a CPU ID to exclude instead of just a
boolean.  This isn't any more complex for the API to handle and allows the
hardlockup detector to exclude a different CPU (the one it already did a
trace for) without needing to find space for a CPU mask.

Arguably, this new API also encourages safer behavior.  Specifically if
the caller wants to avoid tracing the current CPU (maybe because they
already traced the current CPU) this makes it more obvious to the caller
that they need to make sure that the current CPU ID can't change.

[akpm@linux-foundation.org: fix trigger_allbutcpu_cpu_backtrace() stub]
Link: https://lkml.kernel.org/r/20230804065935.v4.1.Ia35521b91fc781368945161d7b28538f9996c182@changeid
Signed-off-by: Douglas Anderson &lt;dianders@chromium.org&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: kernel test robot &lt;lkp@intel.com&gt;
Cc: Lecopzer Chen &lt;lecopzer.chen@mediatek.com&gt;
Cc: Petr Mladek &lt;pmladek@suse.com&gt;
Cc: Pingfan Liu &lt;kernelfans@gmail.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>x86/nmi: Print reasons why backtrace NMIs are ignored</title>
<updated>2023-01-19T23:55:12Z</updated>
<author>
<name>Paul E. McKenney</name>
<email>paulmck@kernel.org</email>
</author>
<published>2022-12-17T00:52:01Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=344da544f177f919cf6919e5abcd388f27aa53db'/>
<id>urn:sha1:344da544f177f919cf6919e5abcd388f27aa53db</id>
<content type='text'>
Instrument nmi_trigger_cpumask_backtrace() to dump out diagnostics based
on evidence accumulated by exc_nmi().  These diagnostics are dumped for
CPUs that ignored an NMI backtrace request for more than 10 seconds.

[ paulmck: Apply Ingo Molnar feedback. ]

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: &lt;x86@kernel.org&gt;
Reviewed-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
</entry>
<entry>
<title>printk: rename cpulock functions</title>
<updated>2022-04-22T19:30:57Z</updated>
<author>
<name>John Ogness</name>
<email>john.ogness@linutronix.de</email>
</author>
<published>2022-04-21T21:22:36Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=faebd693c59387b7b765fab64b543855e15a91b4'/>
<id>urn:sha1:faebd693c59387b7b765fab64b543855e15a91b4</id>
<content type='text'>
Since the printk cpulock is CPU-reentrant and since it is used
in all contexts, its usage must be carefully considered and
most likely will require programming locklessly. To avoid
mistaking the printk cpulock as a typical lock, rename it to
cpu_sync. The main functions then become:

    printk_cpu_sync_get_irqsave(flags);
    printk_cpu_sync_put_irqrestore(flags);

Add extra notes of caution in the function description to help
developers understand the requirements for correct usage.

Signed-off-by: John Ogness &lt;john.ogness@linutronix.de&gt;
Reviewed-by: Petr Mladek &lt;pmladek@suse.com&gt;
Signed-off-by: Petr Mladek &lt;pmladek@suse.com&gt;
Link: https://lore.kernel.org/r/20220421212250.565456-2-john.ogness@linutronix.de
</content>
</entry>
<entry>
<title>printk: restore flushing of NMI buffers on remote CPUs after NMI backtraces</title>
<updated>2021-11-10T15:12:00Z</updated>
<author>
<name>Nicholas Piggin</name>
<email>npiggin@gmail.com</email>
</author>
<published>2021-11-07T04:51:16Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=5d5e4522a7f404d1a96fd6c703989d32a9c9568d'/>
<id>urn:sha1:5d5e4522a7f404d1a96fd6c703989d32a9c9568d</id>
<content type='text'>
printk from NMI context relies on irq work being raised on the local CPU
to print to console. This can be a problem if the NMI was raised by a
lockup detector to print lockup stack and regs, because the CPU may not
enable irqs (because it is locked up).

Introduce printk_trigger_flush() that can be called another CPU to try
to get those messages to the console, call that where printk_safe_flush
was previously called.

Fixes: 93d102f094be ("printk: remove safe buffers")
Cc: stable@vger.kernel.org # 5.15
Signed-off-by: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Reviewed-by: Petr Mladek &lt;pmladek@suse.com&gt;
Reviewed-by: John Ogness &lt;john.ogness@linutronix.de&gt;
Signed-off-by: Petr Mladek &lt;pmladek@suse.com&gt;
Link: https://lore.kernel.org/r/20211107045116.1754411-1-npiggin@gmail.com
</content>
</entry>
<entry>
<title>lib/nmi_backtrace: Serialize even messages about idle CPUs</title>
<updated>2021-07-30T07:25:34Z</updated>
<author>
<name>Petr Mladek</name>
<email>pmladek@suse.com</email>
</author>
<published>2021-07-27T08:09:39Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=26d1982fd17c2cac77f9cf764255362ccb28fe49'/>
<id>urn:sha1:26d1982fd17c2cac77f9cf764255362ccb28fe49</id>
<content type='text'>
The commit 55d6af1d66885059ffc2a ("lib/nmi_backtrace: explicitly serialize
banner and regs") serialized backtraces from more CPUs using the re-entrant
printk_printk_cpu lock. It was a preparation step for removing the obsolete
nmi_safe buffers.

The single-line messages about idle CPUs were not serialized against other
CPUs and might appear in the middle of backtrace from another CPU,
for example:

[56394.590068] NMI backtrace for cpu 2
[56394.590069] CPU: 2 PID: 444 Comm: systemd-journal Not tainted 5.14.0-rc1-default+ #268
[56394.590071] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
[56394.590072] RIP: 0010:lock_is_held_type+0x0/0x120
[56394.590071] NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0xb/0x10
[56394.590076] Code: a2 38 ff 0f 0b 8b 44 24 04 eb bd 48 8d ...
[56394.590077] RSP: 0018:ffffab02c07c7e68 EFLAGS: 00000246
[56394.590079] RAX: 0000000000000000 RBX: ffff9a7bc0ec8a40 RCX: ffffffffaab8eb40

It might cause confusion what CPU the following lines belongs to and
whether the backtraces are really serialized.

Prevent the confusion and serialize also the single line message against
other CPUs.

Fixes: 55d6af1d66885059ffc2a ("lib/nmi_backtrace: explicitly serialize banner and regs")
Reviewed-by: John Ogness &lt;john.ogness@linutronix.de&gt;
Reviewed-by: Sergey Senozhatsky &lt;senozhatsky@chromium.org&gt;
Signed-off-by: Petr Mladek &lt;pmladek@suse.com&gt;
Link: https://lore.kernel.org/r/20210727080939.27193-1-pmladek@suse.com
</content>
</entry>
<entry>
<title>printk: remove safe buffers</title>
<updated>2021-07-26T13:09:34Z</updated>
<author>
<name>John Ogness</name>
<email>john.ogness@linutronix.de</email>
</author>
<published>2021-07-15T19:33:56Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=93d102f094be9beab28e5afb656c188b16a3793b'/>
<id>urn:sha1:93d102f094be9beab28e5afb656c188b16a3793b</id>
<content type='text'>
With @logbuf_lock removed, the high level printk functions for
storing messages are lockless. Messages can be stored from any
context, so there is no need for the NMI and safe buffers anymore.
Remove the NMI and safe buffers.

Although the safe buffers are removed, the NMI and safe context
tracking is still in place. In these contexts, store the message
immediately but still use irq_work to defer the console printing.

Since printk recursion tracking is in place, safe context tracking
for most of printk is not needed. Remove it. Only safe context
tracking relating to the console and console_owner locks is left
in place. This is because the console and console_owner locks are
needed for the actual printing.

Signed-off-by: John Ogness &lt;john.ogness@linutronix.de&gt;
Reviewed-by: Petr Mladek &lt;pmladek@suse.com&gt;
Signed-off-by: Petr Mladek &lt;pmladek@suse.com&gt;
Link: https://lore.kernel.org/r/20210715193359.25946-4-john.ogness@linutronix.de
</content>
</entry>
<entry>
<title>lib/nmi_backtrace: explicitly serialize banner and regs</title>
<updated>2021-07-26T13:07:15Z</updated>
<author>
<name>John Ogness</name>
<email>john.ogness@linutronix.de</email>
</author>
<published>2021-07-15T19:33:54Z</published>
<link rel='alternate' type='text/html' href='https://universe.0xinfinity.dev/distro/kernel/commit/?id=55d6af1d66885059ffc2ac23083de52d12be63bb'/>
<id>urn:sha1:55d6af1d66885059ffc2ac23083de52d12be63bb</id>
<content type='text'>
Currently the nmi_backtrace is serialized against other CPUs because
the messages are sent to the NMI buffers. Once these buffers are
removed, only the dumped stack will be serialized against other CPUs
(via the printk_cpu_lock).

Also serialize the nmi_backtrace banner and regs using the
printk_cpu_lock so that per-CPU serialization will be preserved even
after the NMI buffers are removed.

Signed-off-by: John Ogness &lt;john.ogness@linutronix.de&gt;
Reviewed-by: Petr Mladek &lt;pmladek@suse.com&gt;
Signed-off-by: Petr Mladek &lt;pmladek@suse.com&gt;
Link: https://lore.kernel.org/r/20210715193359.25946-2-john.ogness@linutronix.de
</content>
</entry>