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path: root/drivers/xen/grant-dma-iommu.c
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2024-03-13xen/grant-dma-iommu: Convert to platform remove callback returning voidUwe Kleine-König1-4/+2
The .remove() callback for a platform driver returns an int which makes many driver authors wrongly assume it's possible to do error handling by returning an error code. However the value returned is ignored (apart from emitting a warning) and this typically results in resource leaks. To improve here there is a quest to make the remove callback return void. In the first step of this quest all drivers are converted to .remove_new(), which already returns void. Eventually after all drivers are converted, .remove_new() will be renamed to .remove(). Trivially convert this driver from always returning zero in the remove callback to the void returning variant. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20240307181135.191192-2-u.kleine-koenig@pengutronix.de Signed-off-by: Juergen Gross <jgross@suse.com>
2023-02-13xen/grant-dma-iommu: Implement a dummy probe_device() callbackOleksandr Tyshchenko1-2/+9
Update stub IOMMU driver (which main purpose is to reuse generic IOMMU device-tree bindings by Xen grant DMA-mapping layer on Arm) according to the recent changes done in the following commit 57365a04c921 ("iommu: Move bus setup to IOMMU device registration"). With probe_device() callback being called during IOMMU device registration, the uninitialized callback just leads to the "kernel NULL pointer dereference" issue during boot. Fix that by adding a dummy callback. Looks like the release_device() callback is not mandatory to be implemented as IOMMU framework makes sure that callback is initialized before dereferencing. Reported-by: Viresh Kumar <viresh.kumar@linaro.org> Fixes: 57365a04c921 ("iommu: Move bus setup to IOMMU device registration") Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Tested-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/20230208153649.3604857-1-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>
2022-06-06xen/grant-dma-iommu: Introduce stub IOMMU driverOleksandr Tyshchenko1-0/+78
In order to reuse generic IOMMU device tree bindings by Xen grant DMA-mapping layer we need to add this stub driver from a fw_devlink perspective (grant-dma-ops cannot be converted into the proper IOMMU driver). Otherwise, just reusing IOMMU bindings (without having a corresponding driver) leads to the deferred probe timeout afterwards, because the IOMMU device never becomes available. This stub driver does nothing except registering empty iommu_ops, the upper layer "of_iommu" will treat this as NO_IOMMU condition and won't return -EPROBE_DEFER. As this driver is quite different from the most hardware IOMMU implementations and only needed in Xen guests, place it in drivers/xen directory. The subsequent commit will make use of it. Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/1654197833-25362-7-git-send-email-olekstysh@gmail.com Signed-off-by: Juergen Gross <jgross@suse.com>