On Tue, Dec 13, 2016 at 07:21:48PM +0800, Boqun Feng wrote: > On Tue, Dec 13, 2016 at 10:56:46AM +0000, Colin King wrote: > > From: Colin Ian King <[email protected]> > > > > mask and bit are unsigned longs, so if bit is 31 we end up sign > > extending the 1 and mask ends up as 0xffffffff80000000. Fix this > > by explicitly adding integer suffix UL ensure 1 is a unsigned long > > rather than an signed int. > > > > Right, you are, and the tool is ;-) > > If @bit is greater than 32, we even got an undefined behavior in C ;-( > This is my careless mistake, thank you for finding it out and fix it! > > > Issue found with static analysis with CoverityScan, CID 1388564 > > > > Fixes: 8965c3ce4718754db ("rcu: Use leaf_node_for_each_mask_possible_cpu() > > in force_qs_rnp()") > > Signed-off-by: Colin Ian King <[email protected]> > > I think Paul only queued that for running tests and I have almost > finished a v2. I will fold your fix in my patch and add your SoB along > with mine, does that work for you? > > TBH, this situation is kinda new to me, so if anyone has any suggestion, > please let me know ;-) > > Regards, > Boqun > > > --- > > kernel/rcu/tree.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > index 10162ac..6ecedd8 100644 > > --- a/kernel/rcu/tree.c > > +++ b/kernel/rcu/tree.c > > @@ -3051,7 +3051,7 @@ static void force_qs_rnp(struct rcu_state *rsp, > > > > leaf_node_for_each_mask_possible_cpu(rnp, rnp->qsmask, bit, cpu) > > if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj)) > > - mask |= 1 << bit; > > + mask |= 1UL << bit;
Hmm.. Seems using BIT() here is a good idea, and maybe rename bit as
grp_idx or something.
Naming, naming, naming..
Regards,
Boqun
> >
> > if (mask != 0) {
> > /* Idle/offline CPUs, report (releases rnp->lock. */
> > --
> > 2.10.2
> >
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