On Fri, May 21, 2021 at 02:11:45PM -0500, Josh Poimboeuf wrote: > On Fri, May 21, 2021 at 01:59:16PM -0500, Madhavan T. Venkataraman wrote: > > > > > > On 5/21/21 1:48 PM, Josh Poimboeuf wrote: > > > On Fri, May 21, 2021 at 06:53:18PM +0100, Mark Brown wrote: > > >> On Fri, May 21, 2021 at 12:47:13PM -0500, Madhavan T. Venkataraman wrote: > > >>> On 5/21/21 12:42 PM, Mark Brown wrote: > > >> > > >>>> Like I say we may come up with some use for the flag in error cases in > > >>>> future so I'm not opposed to keeping the accounting there. > > >> > > >>> So, should I leave it the way it is now? Or should I not set reliable = false > > >>> for errors? Which one do you prefer? > > >> > > >>> Josh, > > >> > > >>> Are you OK with not flagging reliable = false for errors in unwind_frame()? > > >> > > >> I think it's fine to leave it as it is. > > > > > > Either way works for me, but if you remove those 'reliable = false' > > > statements for stack corruption then, IIRC, the caller would still have > > > some confusion between the end of stack error (-ENOENT) and the other > > > errors (-EINVAL). > > > > > > > I will leave it the way it is. That is, I will do reliable = false on errors > > like you suggested. > > > > > So the caller would have to know that -ENOENT really means success. > > > Which, to me, seems kind of flaky. > > > > > > > Actually, that is why -ENOENT was introduced - to indicate successful > > stack trace termination. A return value of 0 is for continuing with > > the stack trace. A non-zero value is for terminating the stack trace. > > > > So, either we return a positive value (say 1) to indicate successful > > termination. Or, we return -ENOENT to say no more stack frames left. > > I guess -ENOENT was chosen. > > I see. So it's a tri-state return value, and frame->reliable is > intended to be a private interface not checked by the callers. Or is frame->reliable supposed to be checked after all? Looking at the code again, I'm not sure. Either way it would be good to document the interface more clearly in a comment above the function. -- Josh
