| Message ID | 20180110155853.32348-28-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Christoph Hellwig <hch@lst.de> writes: > Instead of handcoded non-null checks always initialize ki_list to an > empty list and use list_empty / list_empty_careful on it. Yeah, who knows why list_empty wasn't used from the beginning. In the past, tricks were played by overwriting list pointers with non-null, but that wasn't the case here. > While we're at it also error out on a double call to > kiocb_set_cancel_fn instead of ignoring it. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > fs/aio.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/fs/aio.c b/fs/aio.c > index 496b50f9e9b1..fe241b5b44b2 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -555,13 +555,12 @@ void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel) > struct kioctx *ctx = req->ki_ctx; > unsigned long flags; > > - spin_lock_irqsave(&ctx->ctx_lock, flags); > - > - if (!req->ki_list.next) > - list_add(&req->ki_list, &ctx->active_reqs); > + if (WARN_ON_ONCE(!list_empty(&req->ki_list))) > + return; > > + spin_lock_irqsave(&ctx->ctx_lock, flags); > + list_add_tail(&req->ki_list, &ctx->active_reqs); > req->ki_cancel = cancel; So, this changes behavior from quietly overwriting the prior cancel function to not doing it. I don't think it matters one bit, though. Callers shouldn't do that. Acked-by: Jeff Moyer <jmoyer@redhat.com>
diff --git a/fs/aio.c b/fs/aio.c index 496b50f9e9b1..fe241b5b44b2 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -555,13 +555,12 @@ void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel) struct kioctx *ctx = req->ki_ctx; unsigned long flags; - spin_lock_irqsave(&ctx->ctx_lock, flags); - - if (!req->ki_list.next) - list_add(&req->ki_list, &ctx->active_reqs); + if (WARN_ON_ONCE(!list_empty(&req->ki_list))) + return; + spin_lock_irqsave(&ctx->ctx_lock, flags); + list_add_tail(&req->ki_list, &ctx->active_reqs); req->ki_cancel = cancel; - spin_unlock_irqrestore(&ctx->ctx_lock, flags); } EXPORT_SYMBOL(kiocb_set_cancel_fn); @@ -1034,7 +1033,7 @@ static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx) goto out_put; percpu_ref_get(&ctx->reqs); - + INIT_LIST_HEAD(&req->ki_list); req->ki_ctx = ctx; return req; out_put: @@ -1080,7 +1079,7 @@ static void aio_complete(struct aio_kiocb *iocb, long res, long res2) unsigned tail, pos, head; unsigned long flags; - if (iocb->ki_list.next) { + if (!list_empty_careful(iocb->ki_list.next)) { unsigned long flags; spin_lock_irqsave(&ctx->ctx_lock, flags);
Instead of handcoded non-null checks always initialize ki_list to an empty list and use list_empty / list_empty_careful on it. While we're at it also error out on a double call to kiocb_set_cancel_fn instead of ignoring it. Signed-off-by: Christoph Hellwig <hch@lst.de> --- fs/aio.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)