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>
This commit is contained in:
Christoph Hellwig
2020-06-10 18:42:06 -07:00
committed by Linus Torvalds
parent 4dbe59a6ae
commit f5678e7f2a
12 changed files with 40 additions and 41 deletions

View File

@@ -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 */