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    SubjectRe: [replace-alexv-buffer.c-patch] Re: [PATCH] Several bad bugs in fs/*
    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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