Re: [RFC PATCH] add wait_event_*_lock() functions

[Nishanth Aravamudan <nacc@us.ibm.com>]

On Fri, Feb 11, 2005 at 01:07:08AM -0600, Al Borchers wrote:
> 
> 
> On Thursday 10 February 2005 9:39 am, Nishanth Aravamudan wrote:
> >> It came up on IRC that the wait_cond*() functions from
> >> usb/serial/gadget.c could be useful in other parts of the kernel. Does
> >> the following patch make sense towards this?
> 
> Sure, if people want to use these.
> 
> I did not push them because they seemed a bit "heavy weight",
> but the construct is useful and general.

I think that is very much the case. As I was setting up patches for the
Kernel-Janitors to clean up the wait-queue usage in the kernel, I found
I was unable to use wait_event*(), as locks needed to be
released/grabbed around the sleep. wait_event_*_lock() fixes this
problem, clearly :)

> The docs should explain that the purpose is to wait atomically on
> a complex condition, and that the usage pattern is to hold the
> lock when using the wait_event_* functions or when changing any
> variable that might affect the condition and waking up the waiting
> processes.

I will submit a new patch which documents the general structure of the
wait_event_*() class of functions, including what you have written.

Thanks,
Nish