Messages in this thread | | | Date | Thu, 13 Jun 2013 09:56:11 +0200 (CEST) | From | Julia Lawall <> | Subject | Re: [RFC] PTR_ERR: return 0 if ptr isn't an error value. |
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On Thu, 13 Jun 2013, Michael S. Tsirkin wrote:
> On Thu, Jun 13, 2013 at 02:07:40PM +0930, Rusty Russell wrote: > > Julia Lawall <julia.lawall@lip6.fr> writes: > > > On Mon, 3 Jun 2013, Uwe Kleine-König wrote: > > > For a random example, here is a function that currently uses PTR_RET: > > > > Heheh, nice choice: I think I wrote that code originally :) > > > > > static int __net_init iptable_raw_net_init(struct net *net) > > > { > > > struct ipt_replace *repl; > > > > > > repl = ipt_alloc_initial_table(&packet_raw); > > > if (repl == NULL) > > > return -ENOMEM; > > > net->ipv4.iptable_raw = > > > ipt_register_table(net, &packet_raw, repl); > > > kfree(repl); > > > return PTR_RET(net->ipv4.iptable_raw); > > > } > > > > > > If it becomes return PTR_ERR(...); at the end, won't it look like the > > > function always fails? > > > > That is a valid point, though in this case the reader will know that > > can't be the case. > > > > On the other hand, there's an incremental learning curve cost to every > > convenience function we add. There are only 50 places where we use > > PTR_RET(), so it's not saving us very much typing over the clearest > > solution: open-coding the test. > > > > I think using PTR_ERR() is a less bad solution than promoting PTR_RET, > > which has a non-obvious name. > > > > Cheers, > > Rusty. > > Will a longer name make the function more obvious? > PTR_ERR_OR_ZERO() ? > PTR_ERR0() ? > PTR_ERR() can then stay simple for cases where we know we > are on the error path.
I was thinking of something along those lines. And in that case, PTR_ERR could stay without the additional test.
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