Messages in this thread | | | Subject | Re: [PATCH] iommu/dma: Fix check for error return from iommu_map_sg_atomic() | From | Niklas Schnelle <> | Date | Tue, 17 May 2022 12:17:29 +0200 |
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On Tue, 2022-05-17 at 10:36 +0200, Christoph Hellwig wrote: > On Fri, May 13, 2022 at 05:39:48PM +0200, Niklas Schnelle wrote: > > In __iommu_dma_alloc_noncontiguous() the value returned by > > iommu_map_sg_atomic() is checked for being smaller than size. Before > > commit ad8f36e4b6b1 ("iommu: return full error code from > > iommu_map_sg[_atomic]()") this simply checked if the requested size was > > successfully mapped. > > > > After that commit iommu_map_sg_atomic() may also return a negative > > error value. In principle this too would be covered by the existing > > check. There is one problem however, as size is of type size_t while the > > return type of iommu_map_sg_atomic() is now of type ssize_t the latter gets > > converted to size_t and negative error values end up as very large > > positive values making the check succeed. Fix this by making the return > > type visible with a local variable and add an explicit cast to ssize_t. > > > > Fixes: ad8f36e4b6b1 ("iommu: return full error code from iommu_map_sg[_atomic]()") > > Cc: stable@vger.kernel.org > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > > I don't see what the point of the newly added local variable is here. > Just casting size should be all that is needed as far as I can tell.
No technical reason just found it easier to read and more descriptive. I'll sent a v2 with just the cast, it does simplify the commit message.
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