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From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	John Ogness <john.ogness@linutronix.de>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org
Subject: Re: consoles: was: [PATCH next v2 3/3] printk: remove logbuf_lock, add syslog_lock
Date: Wed, 9 Dec 2020 05:51:37 +0900	[thread overview]
Message-ID: <X8/nWUD1bKeQQ74Z@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <X836yrIxyIp5y+Qq@alley>

On (20/12/07 10:50), Petr Mladek wrote:
[..]
> > and then some call into the scheduler
> > (or other kernel core functions) under semaphore's spin_lock.
> > For instance
> > 
> > 	up()
> > 	 raw_spin_lock_irqsave(&sem->lock)
> > 	   __up()
> > 	     wake_up_process()
> > 	       try_to_wake_up()
> 
> This problem is partly solved by printk_deferred(). In each
> case, printk_safe() does not help here.

printk_deferred() has never been used in all the critical code paths.
So I think printk_safe does help here; it takes care of all the
remaining cases, that are not "partly solved by printk_deferred()".

> I still do _not_ see a reason to keep printk_safe()!

Not sure I'm following, sorry. To put it simply - we better keep
printk_safe until "new recursion prevention" >= printk_safe().
In this patch set "new recursion prevention" < printk_safe().

	-ss

      reply	other threads:[~2020-12-08 20:52 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-01 20:53 [PATCH next v2 0/3] printk: remove logbuf_lock John Ogness
2020-12-01 20:53 ` [PATCH next v2 1/3] printk: inline log_output(),log_store() in vprintk_store() John Ogness
2020-12-03 15:57   ` Petr Mladek
2020-12-03 16:25     ` John Ogness
2020-12-04  6:13       ` Sergey Senozhatsky
2020-12-04  8:26       ` Petr Mladek
2020-12-01 20:53 ` [PATCH next v2 2/3] printk: change @clear_seq to atomic64_t John Ogness
2020-12-04  9:12   ` Petr Mladek
2020-12-06 20:23     ` John Ogness
2020-12-07  9:34       ` Peter Zijlstra
2020-12-07 10:03         ` John Ogness
2020-12-07 12:56           ` Peter Zijlstra
2020-12-07 12:56           ` Petr Mladek
2020-12-07 16:46           ` David Laight
2020-12-08 20:34     ` Sergey Senozhatsky
2020-12-08 22:30       ` John Ogness
2020-12-09  1:04         ` Sergey Senozhatsky
2020-12-09  8:16         ` Peter Zijlstra
2020-12-09  9:22           ` Sergey Senozhatsky
2020-12-09 10:46             ` Sergey Senozhatsky
2020-12-09 11:00               ` Peter Zijlstra
2020-12-09 11:28                 ` Sergey Senozhatsky
2020-12-09 12:29                   ` Peter Zijlstra
2020-12-09  8:07       ` Peter Zijlstra
2020-12-01 20:53 ` [PATCH next v2 3/3] printk: remove logbuf_lock, add syslog_lock John Ogness
2020-12-04  6:41   ` Sergey Senozhatsky
2020-12-06 20:44     ` John Ogness
2020-12-04 15:52   ` devkmsg: was " Petr Mladek
2020-12-06 20:51     ` John Ogness
2020-12-07  9:56       ` Petr Mladek
2020-12-04 15:57   ` syslog: was: " Petr Mladek
2020-12-06 21:06     ` John Ogness
2020-12-07 10:01       ` Petr Mladek
2020-12-04 16:10   ` recursion handling: " Petr Mladek
2020-12-05  4:25     ` Sergey Senozhatsky
2020-12-06 22:08       ` John Ogness
2020-12-05  9:41     ` Sergey Senozhatsky
2020-12-06 22:17       ` John Ogness
2020-12-06 21:44     ` John Ogness
2020-12-07 11:17       ` Petr Mladek
2020-12-04 16:15   ` vprintk_store: was: " Petr Mladek
2020-12-06 22:30     ` John Ogness
2020-12-07 12:46       ` Petr Mladek
2020-12-04 16:19   ` consoles: " Petr Mladek
2020-12-05  4:39     ` Sergey Senozhatsky
2020-12-07  9:50       ` Petr Mladek
2020-12-08 20:51         ` Sergey Senozhatsky [this message]

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