Commit f5678e7f authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Linus Torvalds
Browse files

kernel: better document the use_mm/unuse_mm API contract 

Switch the function documentation to kerneldoc comments, and add
WARN_ON_ONCE asserts that the calling thread is a kernel thread and does
not have ->mm set (or has ->mm set in the case of unuse_mm).

Also give the functions a kthread_ prefix to better document the use case.

[hch@lst.de: fix a comment typo, cover the newly merged use_mm/unuse_mm caller in vfio]
  Link: http://lkml.kernel.org/r/20200416053158.586887-3-hch@lst.de
[sfr@canb.auug.org.au: powerpc/vas: fix up for {un}use_mm() rename]
  Link: http://lkml.kernel.org/r/20200422163935.5aa93ba5@canb.auug.org.au



Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Tested-by: default avatarJens Axboe <axboe@kernel.dk>
Reviewed-by: default avatarJens Axboe <axboe@kernel.dk>
Acked-by: default avatarFelix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [usb]
Acked-by: default avatarHaren Myneni <haren@linux.ibm.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Link: http://lkml.kernel.org/r/20200404094101.672954-6-hch@lst.de


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4dbe59a6

arch/powerpc/platforms/powernv/vas-fault.c

+2 −2
Original line number Diff line number Diff line
@@ -127,7 +127,7 @@ static void update_csb(struct vas_window *window, 
		return;

	}



	use_mm(window->mm);

	kthread_use_mm(window->mm);

	rc = copy_to_user(csb_addr, &csb, sizeof(csb));

	/*

	 * User space polls on csb.flags (first byte). So add barrier
@@ -139,7 +139,7 @@ static void update_csb(struct vas_window *window, 
		smp_mb();

		rc = copy_to_user(csb_addr, &csb, sizeof(u8));

	}

	unuse_mm(window->mm);

	kthread_unuse_mm(window->mm);

	put_task_struct(tsk);



	/* Success */

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h

+2 −2
Original line number Diff line number Diff line
@@ -197,9 +197,9 @@ uint8_t amdgpu_amdkfd_get_xgmi_hops_count(struct kgd_dev *dst, struct kgd_dev *s 
			if ((mmptr) == current->mm) {			\

				valid = !get_user((dst), (wptr));	\

			} else if (current->mm == NULL) {		\

				use_mm(mmptr);				\

				kthread_use_mm(mmptr);			\

				valid = !get_user((dst), (wptr));	\

				unuse_mm(mmptr);			\

				kthread_unuse_mm(mmptr);		\

			}						\

			pagefault_enable();				\

		}							\

drivers/usb/gadget/function/f_fs.c

+2 −2
Original line number Diff line number Diff line
@@ -827,9 +827,9 @@ static void ffs_user_copy_worker(struct work_struct *work) 
		mm_segment_t oldfs = get_fs();



		set_fs(USER_DS);

		use_mm(io_data->mm);

		kthread_use_mm(io_data->mm);

		ret = ffs_copy_to_iter(io_data->buf, ret, &io_data->data);

		unuse_mm(io_data->mm);

		kthread_unuse_mm(io_data->mm);

		set_fs(oldfs);

	}

drivers/usb/gadget/legacy/inode.c

+2 −2
Original line number Diff line number Diff line
@@ -462,9 +462,9 @@ static void ep_user_copy_worker(struct work_struct *work) 
	struct kiocb *iocb = priv->iocb;

	size_t ret;



	use_mm(mm);

	kthread_use_mm(mm);

	ret = copy_to_iter(priv->buf, priv->actual, &priv->to);

	unuse_mm(mm);

	kthread_unuse_mm(mm);

	if (!ret)

		ret = -EFAULT;

drivers/vfio/vfio_iommu_type1.c

+2 −2
Original line number Diff line number Diff line
@@ -2817,7 +2817,7 @@ static int vfio_iommu_type1_dma_rw_chunk(struct vfio_iommu *iommu, 
		return -EPERM;



	if (kthread)

		use_mm(mm);

		kthread_use_mm(mm);

	else if (current->mm != mm)

		goto out;
@@ -2844,7 +2844,7 @@ static int vfio_iommu_type1_dma_rw_chunk(struct vfio_iommu *iommu, 
		*copied = copy_from_user(data, (void __user *)vaddr,

					   count) ? 0 : count;

	if (kthread)

		unuse_mm(mm);

		kthread_unuse_mm(mm);

out:

	mmput(mm);

	return *copied ? 0 : -EFAULT;

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