Re: CVS commit: src/sys/kern

[yamt%mwd.biglobe.ne.jp@localhost (YAMAMOTO Takashi)]

hi,

> Module Name:  src
> Committed By: pooka
> Date:         Mon Mar 11 21:37:54 UTC 2013
> 
> Modified Files:
>       src/sys/kern: subr_pool.c
> 
> Log Message:
> In pool_cache_put_slow(), pool_get() can block (it does mutex_enter()),
> so we need to retry if curlwp took a context switch during the call.
> Otherwise, CPU-local invariants can get screwed up:
> 
>     panic: kernel diagnostic assertion "cur->pcg_avail == cur->pcg_size" 
> failed
> 
> This is (was) very easy to reproduce by just running:
> 
>   while : ; do RUMP_NCPU=32 ./a.out ; done
> 
> where a.out only calls rump_init().  But, any situation there's contention
> and a pool doesn't have emptygroups would do.

depending on mutex_init's arguments (type and ipl), a mutex can be
spin or adaptive.
rump mutex implementation should honor the behaviour, i guess.

YAMAMOTO Takashi

> 
> 
> To generate a diff of this commit:
> cvs rdiff -u -r1.199 -r1.200 src/sys/kern/subr_pool.c
> 
> Please note that diffs are not public domain; they are subject to the
> copyright notices on the relevant files.