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io_uring: comment on kfree(iovec) checks

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kfree() handles NULL pointers well, but io_{read,write}() checks it
because of performance reasons. Leave a comment there for those who are
tempted to patch it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2020-08-20 11:34:10 +03:00 committed by Jens Axboe
parent bb175342aa
commit f261c16861
1 changed files with 2 additions and 0 deletions
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2
fs/io_uring.c
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@ -3204,6 +3204,7 @@ done:
kiocb_done(kiocb, ret, cs); kiocb_done(kiocb, ret, cs);
ret = 0; ret = 0;
out_free: out_free:
/* it's reportedly faster than delegating the null check to kfree() */
if (iovec) if (iovec)
kfree(iovec); kfree(iovec);
return ret; return ret;
@ -3300,6 +3301,7 @@ copy_iov:
return -EAGAIN; return -EAGAIN;
} }
out_free: out_free:
/* it's reportedly faster than delegating the null check to kfree() */
if (iovec) if (iovec)
kfree(iovec); kfree(iovec);
return ret; return ret;