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    SubjectRe: [PATCH] Intel IOMMU: get_domain_for_dev() leaks a bit of mem if dmar_find_matched_drhd_unit() fails.

    PING

    Any chance we could merge the updated patch below?

    /Jesper


    On Thu, 10 Feb 2011, Jesper Juhl wrote:

    > On Thu, 10 Feb 2011, Alex Williamson wrote:
    >
    > > On Sun, 2011-02-06 at 21:11 +0100, Jesper Juhl wrote:
    > > > I believe that there's a small memory leak in
    > > > drivers/pci/intel-iommu.c:get_domain_for_dev().
    > > >
    > > > If the call to alloc_domain() succeeds but the subsequent call to
    > > > dmar_find_matched_drhd_unit() fails, then the current code will return
    > > > NULL without calling domain_exit(domain) which will leak the memory that
    > > > alloc_domain() allocated.
    > > >
    > > > The easy fix for that is to simply move the call to alloc_domain() below
    > > > the call to dmar_find_matched_drhd_unit() since the latter does not depend
    > > > on the former.
    > > >
    > > > I also made the change of moving the assignment to local variable 'iommu'
    > > > below both calls since there is no point in doing that work if either of
    > > > those those calls fail.
    > > >
    > > > I also changed the 'return NULL' in the dmar_find_matched_drhd_unit()
    > > > failure case to a 'goto error' since I figured that if rechecking
    > > > 'find_domain(pdev)' makes sense after a alloc_domain() failure then it
    > > > would also make sense after a dmar_find_matched_drhd_unit() failure.
    > >
    > > I don't think this change buys us anything. The goto error here seems
    > > to be a hope that another cpu may have beat us and succeeded at
    > > something we failed. In the case of matching the pci device to a drhd,
    > > this should be deterministic (unless maybe we're racing a hot added
    > > drhd). The rest seems fine to me. Thanks,
    > >
    > > Alex
    > >
    >
    > Ok. Updated patch below that leaves out the 'goto error' bit for
    > dmar_find_matched_drhd_unit() failures.
    >
    >
    >
    > There is a small memory leak in
    > drivers/pci/intel-iommu.c:get_domain_for_dev().
    >
    > If the call to alloc_domain() succeeds but the subsequent call to
    > dmar_find_matched_drhd_unit() fails, then the current code will return
    > NULL without calling domain_exit(domain) which will leak the memory that
    > alloc_domain() allocated.
    >
    > The easy fix for that is to simply move the call to alloc_domain() below
    > the call to dmar_find_matched_drhd_unit() since the latter does not depend
    > on the former.
    >
    > Signed-off-by: Jesper Juhl <jj@chaosbits.net>
    > ---
    > intel-iommu.c | 9 ++++-----
    > 1 file changed, 4 insertions(+), 5 deletions(-)
    >
    > diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
    > index 4789f8e..3cfb021 100644
    > --- a/drivers/pci/intel-iommu.c
    > +++ b/drivers/pci/intel-iommu.c
    > @@ -1820,10 +1820,6 @@ static struct dmar_domain *get_domain_for_dev(struct pci_dev *pdev, int gaw)
    > }
    > }
    >
    > - domain = alloc_domain();
    > - if (!domain)
    > - goto error;
    > -
    > /* Allocate new domain for the device */
    > drhd = dmar_find_matched_drhd_unit(pdev);
    > if (!drhd) {
    > @@ -1831,8 +1827,11 @@ static struct dmar_domain *get_domain_for_dev(struct pci_dev *pdev, int gaw)
    > pci_name(pdev));
    > return NULL;
    > }
    > - iommu = drhd->iommu;
    > + domain = alloc_domain();
    > + if (!domain)
    > + goto error;
    >
    > + iommu = drhd->iommu;
    > ret = iommu_attach_domain(domain, iommu);
    > if (ret) {
    > domain_exit(domain);
    >
    >
    >

    --
    Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/
    Don't top-post http://www.catb.org/jargon/html/T/top-post.html
    Plain text mails only, please.



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