Messages in this thread | | | Date | Thu, 22 Apr 1999 23:25:25 +0200 (CEST) | From | Andrea Arcangeli <> | Subject | Re: [replace-alexv-buffer.c-patch] Re: [PATCH] Several bad bugs in fs/* |
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On Thu, 22 Apr 1999, Alexander Viro wrote:
> > >On Thu, 22 Apr 1999, Andrea Arcangeli wrote: > >> >> @@ -653,10 +629,13 @@ >> >> * around on the free list, and we can get in a loop if we are not careful. >> >> */ >> >> for(nlist = 0; nlist < NR_LIST; nlist++) { >> >> + refiled: >> >> bh = lru_list[nlist]; >> >> for (i = nr_buffers_type[nlist]*2 ; --i > 0 ; bh = bhnext) { >> >> if(!bh) >> >> break; >> >> + if (bh->b_list != nlist) >> >> + goto refiled; >> > >> > Ahem... Busy-waiting is fun, ain't it? What did you really mean >> >in the chunk above? >> >> Starting from the second run of the loop bh is == bhnext. But bhnext is >> been moved from the dirty list to the clean list while we was sleeping in >> wait_on_buffer(). So without my patch we could continue browsing the clean >> list instead of continue to browse the dirty list. > >Andrea, look what will happen if lru_list[nlist]->b_list!=nlist. You will >not get to the end of the inner loop - it will just spin. I'll try to look
But lru_list[nlist]->b_list is always == nlist, otherwise the buffer pointed by lru_list[nlist] wouldn't be there ;).
Andrea Arcangeli
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