Well, my earlier find_first_bit() implementation was completely bogus.
My sanity has now returned and I coded this patch below that fixes
find_find_bit() to return "size" if all bits are zero. I have tested it
extensively in userspace and it boots 2.5.44-mm5 which crashed with the earlier
version of the bitops_fix patch. I have coded the assembly routine
as optimal as I could think of and without introducing any new
branches or memory loads.
Along with this patch, I applied the larger_cpu_mask patch to -mm5
and sanity tested both UP and SMP kernels for dcache leaks in a 4CPU P3 box.
An ls -lR and subsequent unmounting of that filesystems showed that
the dentries were correctly getting returned the dcache slab and
that indicates that the larger_cpu_mask patch no longer breaks RCU.
I will do some more testing with this combination later with
rcu_stats applied on this tree (just to be sure), but so far it looks good.
Thanks
-- Dipankar Sarma <dipankar@in.ibm.com> http://lse.sourceforge.net Linux Technology Center, IBM Software Lab, Bangalore, India.bitops_fix.patch -----------------
diff -urN linux-2.5.44-mm5/include/asm-i386/bitops.h linux-2.5.44-mm5-fix/include/asm-i386/bitops.h --- linux-2.5.44-mm5/include/asm-i386/bitops.h Sat Oct 19 09:32:01 2002 +++ linux-2.5.44-mm5-fix/include/asm-i386/bitops.h Sat Oct 26 17:52:09 2002 @@ -311,12 +311,13 @@ "repe; scasl\n\t" "jz 1f\n\t" "leal -4(%%edi),%%edi\n\t" - "bsfl (%%edi),%%eax\n" - "1:\tsubl %%ebx,%%edi\n\t" + "bsfl (%%edi),%%edx\n" + "subl %%ebx,%%edi\n\t" "shll $3,%%edi\n\t" - "addl %%edi,%%eax" + "addl %%edi,%%edx\n\t" + "1:\tmovl %%edx,%%eax\n\t" :"=a" (res), "=&c" (d0), "=&D" (d1) - :"1" ((size + 31) >> 5), "2" (addr), "b" (addr)); + :"1" ((size + 31) >> 5), "2" (addr), "b" (addr), "d" (size)); return res; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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