Messages in this thread | | | Date | Wed, 25 Aug 2010 12:31:52 +0800 | Subject | Re: [PATCH] avoiding the same resource to be inserted | From | Huang Shijie <> |
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On Wed, Aug 25, 2010 at 7:46 AM, Andrew Morton <akpm@linux-foundation.org> wrote: > On Mon, 16 Aug 2010 23:55:38 +0800 > Huang Shijie <shijie8@gmail.com> wrote: > >> If the same resource is inserted to the resource tree >> (maybe not on purpose), a dead loop will be created. In this situation, >> The kernel does not report any warning or error :( >> >> The command below will show a endless print. >> #cat /proc/iomem > > OK, we shouldn't do that. > >> So, adding the check for the same resource is needed for the stability >> and reliability of the kernel. >> >> Signed-off-by: Huang Shijie <shijie8@gmail.com> >> --- >> kernel/resource.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/kernel/resource.c b/kernel/resource.c >> index 7b36976..60daab4 100644 >> --- a/kernel/resource.c >> +++ b/kernel/resource.c >> @@ -451,7 +451,7 @@ static struct resource * __insert_resource(struct resource *parent, struct resou >> if (!first) >> return first; >> >> - if (first == parent) >> + if (first == parent || first == new) >> return first; > > However, inserting the same thing twice _is_ a bug, and we shouldn't > silently accept it like this. We should tell the programmer!
Indeed, this is a bug caused by the driver programmer.I had spent nearly two day to find it in my colleague's code.
> > But we can recover from the situation so let's not kill the box. How > does this look? > > --- a/kernel/resource.c~kernel-resourcec-handle-reinsertion-of-an-already-inserted-resource > +++ a/kernel/resource.c > @@ -453,6 +453,8 @@ static struct resource * __insert_resour > > if (first == parent) > return first; > + if (WARN_ON(first == new)) /* duplicated insertion */ > + return first; >
Yes. This one is better. Many drivers do not check the returned value of insert_resouce().
> if ((first->start > new->start) || (first->end < new->end)) > break; > _ > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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