at the moment, i'm working my way through numerous kernel topics in aid of tracking updates for LKD3 and making personal notes. for instance, here's my wiki page for per-CPU variables: http://www.crashcourse.ca/wiki/index.php/Per-CPU_variables as you can see, lots of links to docs and tutorials and excerpts from header and source files, just for my own benefit for the time being and to be organized later. but toward the end, you can read where i'm a bit puzzled by two macros i ran across just this morning that i had never seen before, and defined in <linux/percpu.h>: #define get_cpu_ptr(var) ({ \ preempt_disable(); \ this_cpu_ptr(var); }) #define put_cpu_ptr(var) do { \ (void)(var); \ preempt_enable(); \ } while (0) i don't recall ever seeing a reference to those two macros anywhere i've read, and a tree-wide search shows *very* few uses: $ grep -rw get_cpu_ptr * include/linux/percpu.h:#define get_cpu_ptr(var) ({ \ kernel/events/core.c: cpuctx = get_cpu_ptr(pmu->pmu_cpu_context); kernel/events/core.c: cpuctx = get_cpu_ptr(pmu->pmu_cpu_context); kernel/events/core.c: cpuctx = get_cpu_ptr(pmu->pmu_cpu_context); $ grep -rw put_cpu_ptr * include/linux/percpu.h:#define put_cpu_ptr(var) do { \ kernel/events/core.c: put_cpu_ptr(pmu->pmu_cpu_context); kernel/events/core.c: put_cpu_ptr(pmu->pmu_cpu_context); kernel/events/core.c: put_cpu_ptr(pmu->pmu_cpu_context); $ that's it, that appears to be the extent of usage in the entire kernel source tree. i'm sure i'll figure them out given a bit more time, but anyone want to clarify the purpose of those macros? and perhaps whether they're rarely used because normal kernel programmers shouldn't be using them? thanks. rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ======================================================================== _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
