On Fri, May 02, 2014 at 10:07:33AM -0700, Kamal Mostafa wrote: > Dirk Behme points out that this "Cc: stable" commit breaks the > lttng-modules userspace API when applied to stable kernels. Stable > versions 3.2, 3.8, 3.11, and 3.13 (at least) have all queued it: > > af5040da01ef980670b3741b3e10733ee3e33566 > blktrace: fix accounting of partially completed requests > > > On Thu, 2014-05-01 at 10:28 +0200, Dirk Behme wrote: > > [...] might break the build of the user space lttng-modules > > (lttng-probe-block.c) due the the API change of > > trace_block_rq_complete(). > > > [...] On the other hand, looking into the lttng-modules git > > http://git.lttng.org/?p=lttng-modules.git;a=commitdiff;h=1c53e689434a6bdd7dc3f54c07bfb72750d1d24c > > looks like this is the necessary user space adaption to the kernel > > change? So this looks like that lttng-modules expects a KERNEL_VERSION > > >= (3,15,0) to have this commit? > > > My inclination is that we probably need to revert/drop "af5040d > blktrace: fix accounting..." from the stable kernels to unbreak the > userspace API. Then you will run into this issue with 3.15, when it is released. So might as well be consistant here. Are tracepoints, and the data within them, being considered as a "user api" that we can never change / break anymore? As the current implementation is obviously broken (see the patch for details), why would it make sense to even keep it around in that state? lttng, by using that existing api, is reporting incorrect data, wouldn't it make more sense to fix it up too? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html