On Sun, 24 May 2015, Tejun Heo wrote: > Hello, > > On Sun, May 24, 2015 at 03:07:52PM +0200, Nicholas Mc Guire wrote: > > Type-checking coccinelle spatches are being used to locate type mismatches > > between function signatures and return values in this case this produced: > > ./kernel/cgroup.c:2525 WARNING: return of wrong type > > ssize_t != size_t, > > > > Returning unsigned types converted to a signed type can be problematic > > but in this case the size_t is <= PATH_MAX which is less than ulong/2 so > > the conversion is safe - to make static code checking happy this is > > resolved by an explicit cast and appropriate comment. > > > > Patch was compile tested with x86_64_defconfig (implies CONFIG_CGROUPS=y) > > > > Patch is against 4.1-rc4 (localversion-next is -next-20150522) > > > > Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx> > > --- > > > > Not sure if "cleanups" like this are acceptable - in this case I did not > > find any better way to make static code checkers happy though. > > > > kernel/cgroup.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > > index b91177f..04de621 100644 > > --- a/kernel/cgroup.c > > +++ b/kernel/cgroup.c > > @@ -2523,7 +2523,11 @@ static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, > > sizeof(cgrp->root->release_agent_path)); > > spin_unlock(&release_agent_path_lock); > > cgroup_kn_unlock(of->kn); > > - return nbytes; > > + > > + /* the path of the release notifier is <= PATH_MAX > > + * so "downsizing" to signed long is safe here > > + */ > > + return (ssize_t)nbytes; > > idk, does this actually help anything? This isn't different from any > other implicit type casts. Are we gonna convert all downward implicit > casts to be explicit? > nop not downward but signed/unsigned if it were down it would not be a problem but signed/unsigned can be - for those cases where it can't be fixed up by changing the declarations or return variable types explicit cast might make sense - as noted in the patch Im not sure either if this form of cleanups is helpful. In the kernel core there are about 400 signed/unsigned implicit conversions (about 3k in the entire kernel) which is what Im trying to remove or if that is not possible in a resonable way mark as false positive. thx! hofrat -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
