On Thu, Sep 29, 2016 at 8:06 PM, Joe Perches <joe@xxxxxxxxxxx> wrote: > On Thu, 2016-09-29 at 18:57 +0100, Colin King wrote: >> Currently U300_DMA_CHANNELS is set to 40, meaning that the shift of 1 can >> be more than 32 places, which leads to a 32 bit integer overflow. Fix this >> by casting 1 to a u64 (the same type as started_channels) before shifting >> it. > > trivia: > >> diff --git a/drivers/dma/coh901318.c b/drivers/dma/coh901318.c > [] >> @@ -1353,7 +1353,7 @@ static ssize_t coh901318_debugfs_read(struct file *file, char __user *buf, >> tmp += sprintf(tmp, "DMA -- enabled dma channels\n"); >> >> for (i = 0; i < U300_DMA_CHANNELS; i++) >> - if (started_channels & (1 << i)) >> + if (started_channels & ((u64)1 << i)) > > Using > > if (started_channels & (1ULL << i)) > > would be more common. Even better (IMO): #include <linux/bitops.h> if (started_channels & BIT(i)) Apparently code is there to avoid the bit 31 problem, mea culpa. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
