Please ignore this patch, i have put this patch into another patches series, you can refer to the link below:
https://lore.kernel.org/patchwork/patch/988431/ https://lore.kernel.org/patchwork/patch/988432/ https://lore.kernel.org/patchwork/patch/988433/ Thanks. 在 2018年09月17日 14:20, Lianbo Jiang 写道: > When we walk through iomem resources by calling walk_iomem_res_desc(), the > values of the function parameter may be modified in the while loop of __walk > _iomem_res_desc(), which will cause us to not get the desired result in some > cases. > > At present, it only restores the original value of res->end, but it doesn't > restore the original value of res->flags in the while loop of __walk_iomem > _res_desc(). Whenever the find_next_iomem_res() finds a resource and returns > the result, the original values of this resource will be modified, which might > lead to an error in the next loop. For example: > > The original value of resource flags is: res->flags=0x80000200(initial value) > > p->flags _ 0x81000200 _ _ 0x80000200 _ > / \ / \ > |________|_______A________|____|_....._|______B_________|......___| > 0 0xffffffff > (memory address ranges) > > Note: if ((p->flags & res->flags) != res->flags) continue; > > When the resource A is found, the original value of this resource flags will > be changed to 0x81000200(res->flags=0x81000200), and continue to look for the > next resource, when the loop reaches resource B, it can not get the resource B > any more(you can refer to the for loop of find_next_iomem_res()), because the > value of conditional expression will become true and will also jump the > resource > B. In fact, we should get the resource A and B when we walk through the whole > tree, but it only gets the resource A, the resource B is missed. > > Signed-off-by: Lianbo Jiang <liji...@redhat.com> > --- > kernel/resource.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/resource.c b/kernel/resource.c > index 30e1bc68503b..f5d9fc70a04c 100644 > --- a/kernel/resource.c > +++ b/kernel/resource.c > @@ -375,6 +375,7 @@ static int __walk_iomem_res_desc(struct resource *res, > unsigned long desc, > int (*func)(struct resource *, void *)) > { > u64 orig_end = res->end; > + u64 orig_flags = res->flags; > int ret = -1; > > while ((res->start < res->end) && > @@ -385,6 +386,7 @@ static int __walk_iomem_res_desc(struct resource *res, > unsigned long desc, > > res->start = res->end + 1; > res->end = orig_end; > + res->flags = orig_flags; > } > > return ret; >
