On Tue, 2016-10-04 at 21:06 +0530, Vinod Koul wrote: > On Tue, Oct 04, 2016 at 02:23:51PM +0200, Linus Walleij wrote: > > On Thu, Sep 29, 2016 at 8:06 PM, Joe Perches <[email protected]> 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. > I have already applied this one, so feel free to send this as an update :)
BIT_ULL as it still needs to be u64 not unsigned long. But if a change is really desired, please use it consistently in the entire file and not just this instance.
