On Tue, Apr 02, 2019 at 02:40:54PM -0400, Joel Fernandes wrote: > On Tue, Apr 02, 2019 at 08:23:34AM -0700, Paul E. McKenney wrote: > > On Tue, Apr 02, 2019 at 11:14:40AM -0400, Mathieu Desnoyers wrote: > > > ----- On Apr 2, 2019, at 10:28 AM, paulmck paul...@linux.ibm.com wrote: > > > > > > > Hello! > > > > > > > > This series prohibits use of DEFINE_SRCU() and DEFINE_STATIC_SRCU() > > > > by loadable modules. The reason for this prohibition is the fact > > > > that using these two macros within modules requires that the size of > > > > the reserved region be increased, which is not something we want to > > > > be doing all that often. Instead, loadable modules should define an > > > > srcu_struct and invoke init_srcu_struct() from their module_init > > > > function > > > > and cleanup_srcu_struct() from their module_exit function. Note that > > > > modules using call_srcu() will also need to invoke srcu_barrier() from > > > > their module_exit function. > > > > > > This arbitrary API limitation seems weird. > > > > > > Isn't there a way to allow modules to use DEFINE_SRCU and > > > DEFINE_STATIC_SRCU > > > while implementing them with dynamic allocation under the hood ? > > > > Although call_srcu() already has initialization hooks, some would > > also be required in srcu_read_lock(), and I am concerned about adding > > memory allocation at that point, especially given the possibility > > of memory-allocation failure. And the possibility that the first > > srcu_read_lock() happens in an interrupt handler or similar. > > > > Or am I missing a trick here? > > Hi Paul, > > Which 'reserved region' are you referring to? Isn't this region also > used for non-module cases in which case the same problem applies to > non-modules?
The percpu/module reservation discussed in this thread: https://lore.kernel.org/lkml/c72402f2-967e-cd56-99d8-9139c9e7f...@google.com/T/#mbcacf60ddc0b3fd6e831a3ea71efc90da359a3bf For non-modules, global per-CPU variables are statically allocated. For modules, they must be dynamically allocated at modprobe time, and their size is set by PERCPU_MODULE_RESERVE. Thanx, Paul _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx
