[RFC][PATCH -next 0/2] cond_resched() some of console_trylock callers

From	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Newsgroups	linux.kernel
Subject	[RFC][PATCH -next 0/2] cond_resched() some of console_trylock callers
Date	2016-01-14 06:00 +0100
Message-ID	<qQIaS-1Pl-1@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Hello,

RFC (apologies for sending it during the merge window. no rush)

console_unlock() allows to cond_resched() if its caller has
set `console_may_schedule' to 1 (this functionality present
since commit 'printk: do cond_resched() between lines while
outputting to consoles').

The rules are:
-- console_lock() always sets `console_may_schedule' to 1
-- console_trylock() always sets `console_may_schedule' to 0

However, console_trylock() callers (among them is printk()) are
not necessarily executing in atomic contexts, and some of them
can cond_resched() in console_unlock(). So console_trylock()
can set `console_may_schedule' to 0 only if cond_resched() is
invalid in the current context, and set it to 1 otherwise.

Patch 0001 addresses a theoretical loss of printk messages and,
at the same time, serves as a preparation work for 0002.

Sergey Senozhatsky (2):
  printk: move can_use_console out of console_trylock_for_printk
  printk: set may_schedule for some of console_trylock callers

 kernel/printk/printk.c | 84 ++++++++++++++++++++++++--------------------------
 1 file changed, 40 insertions(+), 44 deletions(-)

-- 
2.7.0

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[RFC][PATCH -next 0/2] cond_resched() some of console_trylock callers Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-14 06:00 +0100
  [RFC][PATCH -next 1/2] printk: move can_use_console out of console_trylock_for_printk Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-14 06:00 +0100
    [PATCH 1/2] printk: move can_use_console out of console_trylock_for_printk Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-14 07:00 +0100
  [RFC][PATCH -next 2/2] printk: set may_schedule for some of console_trylock callers Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-01-14 06:00 +0100

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