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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2017-02-02 18:05:26 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-03 09:56:43 -0800
commit29905b52fad0854351f57bab867647e4982285bf (patch)
tree1c7f135300aa0c3f5b24894f183322a1b16de2b4 /net/nfc/hci/llc.h
parent34e00accf612bc5448ae709245c2b408edf39f46 (diff)
log2: make order_base_2() behave correctly on const input value zero
The function order_base_2() is defined (according to the comment block) as returning zero on input zero, but subsequently passes the input into roundup_pow_of_two(), which is explicitly undefined for input zero. This has gone unnoticed until now, but optimization passes in GCC 7 may produce constant folded function instances where a constant value of zero is passed into order_base_2(), resulting in link errors against the deliberately undefined '____ilog2_NaN'. So update order_base_2() to adhere to its own documented interface. [ See http://marc.info/?l=linux-kernel&m=147672952517795&w=2 and follow-up discussion for more background. The gcc "optimization pass" is really just broken, but now the GCC trunk problem seems to have escaped out of just specially built daily images, so we need to work around it in mainline. - Linus ] Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net/nfc/hci/llc.h')
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