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| author | Christoph Hellwig <hch@lst.de> | 2020-06-10 18:42:06 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-06-10 19:14:18 -0700 |
| commit | f5678e7f2ac31c270334b936352f0ef2fe7dd2b3 (patch) | |
| tree | af5dcb313f3267c70d4bcd9e68a3290e01534a5f /kernel/kthread.c | |
| parent | 4dbe59a6ae358f30b6a9a50406249d54cc954dc1 (diff) | |
| download | lwn-f5678e7f2ac31c270334b936352f0ef2fe7dd2b3.tar.gz lwn-f5678e7f2ac31c270334b936352f0ef2fe7dd2b3.zip | |
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: Christoph Hellwig <hch@lst.de>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [usb]
Acked-by: Haren 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: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/kthread.c')
| -rw-r--r-- | kernel/kthread.c | 33 |
1 files changed, 16 insertions, 17 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c index ce4610316377..8ed4b4fbec7c 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -1208,18 +1208,18 @@ void kthread_destroy_worker(struct kthread_worker *worker) } EXPORT_SYMBOL(kthread_destroy_worker); -/* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * (Note: this routine is intended to be called only - * from a kernel thread context) +/** + * kthread_use_mm - make the calling kthread operate on an address space + * @mm: address space to operate on */ -void use_mm(struct mm_struct *mm) +void kthread_use_mm(struct mm_struct *mm) { struct mm_struct *active_mm; struct task_struct *tsk = current; + WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); + WARN_ON_ONCE(tsk->mm); + task_lock(tsk); active_mm = tsk->active_mm; if (active_mm != mm) { @@ -1236,20 +1236,19 @@ void use_mm(struct mm_struct *mm) if (active_mm != mm) mmdrop(active_mm); } -EXPORT_SYMBOL_GPL(use_mm); +EXPORT_SYMBOL_GPL(kthread_use_mm); -/* - * unuse_mm - * Reverses the effect of use_mm, i.e. releases the - * specified mm context which was earlier taken on - * by the calling kernel thread - * (Note: this routine is intended to be called only - * from a kernel thread context) +/** + * kthread_unuse_mm - reverse the effect of kthread_use_mm() + * @mm: address space to operate on */ -void unuse_mm(struct mm_struct *mm) +void kthread_unuse_mm(struct mm_struct *mm) { struct task_struct *tsk = current; + WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); + WARN_ON_ONCE(!tsk->mm); + task_lock(tsk); sync_mm_rss(mm); tsk->mm = NULL; @@ -1257,7 +1256,7 @@ void unuse_mm(struct mm_struct *mm) enter_lazy_tlb(mm, tsk); task_unlock(tsk); } -EXPORT_SYMBOL_GPL(unuse_mm); +EXPORT_SYMBOL_GPL(kthread_unuse_mm); #ifdef CONFIG_BLK_CGROUP /** |