cvs commit: src/sys/kern kern_sig.c

[Julian Elischer]

David Schultz wrote:

>On Thu, Mar 03, 2005, David Xu wrote:
>  
>
>>
>>This only partly resolves the problem,  if function A call B, B call C,  
>>C is unknown to A,
>>and C does a msleep(),  problem still lhappens.
>>However, if there needs a flag,  I would like  PNOSWAP for msleep just 
>>like PCATCH
>>does.
>>    
>>
>
>You have to worry about that anyway, though.  A and B need to know
>that they're not allowed to hold locks across the calls if C calls
>msleep(), for instance.  Anyway, your proposal if having a flag
>for msleep() is basically the same as my proposal of having a
>separate function.  (The only difference is that adding a separate
>function doesn't break the ABI.)  So it sounds like we're more or
>less in agreement here.
>
>  
>
>>>The alternative, of course, is to just fix the code that assumes
>>>that swapping doesn't exist.
>>>
>>>      
>>>
>>First find all code written in such way, but it is not that easy.
>>    
>>
>
>True.  If we changed msleep() to disable swapping by default, then
>we wouldn't have to worry about correctness problems related to
>missing some.
>  
>

adding the flag to ENABLE swapping would be ABI compatible.