All of lore.kernel.org
 help / color / mirror / Atom feed
From: Heiner Kallweit <hkallweit1@gmail.com>
To: linux-leds@vger.kernel.org
Cc: Jacek Anaszewski <j.anaszewski@samsung.com>
Subject: Locking in LED core really not needed or missing?
Date: Fri, 8 Jan 2016 21:31:12 +0100	[thread overview]
Message-ID: <56901C90.2050801@gmail.com> (raw)

I'm a little puzzled about the more or less completely missing locking in the LED core.

Let's just take led_timer_function as example.
It modifies led_cdev->flags and led_cdev->brightness from soft irq context
(soft blink timer) w/o locking. Accessing these fields is not guaranteed to be atomic
and the function doesn't even use set_bit etc. for modifying the bitmap.

And brightness_set and other exported functions can even be called from
hard irq context (e.g. by triggers).

This seems to be quite unsafe to me. Just think of a soft or hard irq colliding
with a sysfs access. IMHO it's just due to the fact that these collision scenarios
are relatively unlikely that we don't have problems.
Am I missing something or is this actually an open issue?

             reply	other threads:[~2016-01-08 20:31 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-08 20:31 Heiner Kallweit [this message]
2016-01-10  8:17 ` Locking in LED core really not needed or missing? Jacek Anaszewski

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=56901C90.2050801@gmail.com \
    --to=hkallweit1@gmail.com \
    --cc=j.anaszewski@samsung.com \
    --cc=linux-leds@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.