Re: modalias char-major-10-130
From: Guenter Roeck
Date: Fri Jul 05 2013 - 13:18:31 EST
On Wed, Jul 03, 2013 at 02:33:23PM +0200, Jean Delvare wrote:
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Hi Wim,
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All watchdog drivers include:
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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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which causes a modalias char-major-10-130 to be added to every watchdog
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driver module. As a result, any access to /dev/watchdog on a system with
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no watchdog driver loaded and working will result in an attempt to load
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several dozen drivers. At best one or two will actually work, the others
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will:
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* Waste time failing to load.
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* Waste memory succeeding to load but not finding any device to bind to.
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* Pollute the kernel log.
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* Sometimes even load while they should not and break the system. I just
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had a report about advantechwdt doing that on some systems.
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And the attempt order will presumably be random, so it might as well
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load softdog before a hardware-based watchdog which would have been
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preferred.
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This looks so 90s. Drivers for enumerated devices have hardware-based
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modaliases, so char-major-10-130 shouldn't be needed. Other drivers
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should certainly not be loaded randomly if they need to poke the
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hardware to detect the presence of a supported device.
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My opinion is that the char-major-10-130 modalias should ONLY be defined
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by user-space, when the user knows he/she needs a watchdog driver which
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doesn't support auto-loading via hardware-based auto-loading.
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So, can we please get rid of all these
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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR) statements? They do more harm than
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good as far as I can see.
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Agreed.
Can you submit a set of patches ? I'll be happy to add my Reviewed-by: tag
to it. Of course that won't guarantee acceptance ;).
Thanks,
Guenter
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