Messages in this thread | | | Date | Thu, 13 Jun 2013 10:30:47 +0300 | From | "Michael S. Tsirkin" <> | Subject | Re: [RFC] PTR_ERR: return 0 if ptr isn't an error value. |
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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.
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