Am 23.01.2014 10:02, schrieb Takashi Iwai:
At Thu, 23 Jan 2014 09:55:31 +0100, walter harms wrote:
Am 23.01.2014 09:21, schrieb Dan Carpenter:
The test here is intended intended to prevent shift wrapping bugs when we do "1U << idx2". We should consider the number of bits in a u32 instead of the number of bytes.
Fixes: 7bb2491b35a2 ('ALSA: Add kconfig to specify the max card numbers') Signed-off-by: Dan Carpenter dan.carpenter@oracle.com
WARNING: Please check this one carefully because I might be wrong.
diff --git a/sound/core/init.c b/sound/core/init.c index 1351f22f651c..e9e3db321e64 100644 --- a/sound/core/init.c +++ b/sound/core/init.c @@ -183,7 +183,7 @@ int snd_card_create(int idx, const char *xid, if (idx < 0) { for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++) { /* idx == -1 == 0xffff means: take any free slot */
if (idx2 < sizeof(int) && !(idx & (1U << idx2)))
if (idx2 < 32 && !(idx & (1U << idx2))) continue; if (!test_bit(idx2, snd_cards_lock)) { if (!slots[idx2] || !*slots[idx2]) {--
Funny bug, to be 100% sure you could multiply by CHAR_BIT ;)
other code simple does (1UL << (nr & 31)) on the other side a check like:
#if SNDRV_CARDS > 32 # error to much sound #endif
whould give the user a hint what is going on instead of silently ignoring that error.
SNDRV_CARDS can be more than 32. That's why the check was introduced.
yes of cause, but so far i understand this code will do "continue" if SNDRV_CARDS is more that 31, no warning. (warning Start academic discussion): If anyone ever has more that 31 soundcard he will wonder why 31 are working but the rest will remain silent. It would be nice to have a idea that there is an internal limit and it is not sufficient to change SNDRV_CARDS from 8 to 256. (did i understand the code correctly ?) and there is no warning.
re, wh