On 25/04/14 17:45, Steven Rostedt wrote: > On Fri, 25 Apr 2014 17:29:22 +0100 > Daniel Thompson <daniel.thomp...@linaro.org> wrote: > >> If kdb is triggered using SysRq-g then any use of the sr command results >> in the SysRq key table lock being recursively acquired, killing the debug >> session. That patch resolves the problem by introducing a _nolock >> alternative for __handle_sysrq. >> >> Strictly speaking this approach risks racing on the key table when kdb is >> triggered by something other than SysRq-g however in that case any other >> CPU involved should release the spin lock before kgdb parks the slave >> CPUs. > > Is that case documented somewhere in the code comments?
Perhaps not near enough to the _nolock but the primary bit of comment is here (and in same file as kdb_sr). --- cut here --- * kdb_main_loop - After initial setup and assignment of the * controlling cpu, all cpus are in this loop. One cpu is in * control and will issue the kdb prompt, the others will spin * until 'go' or cpu switch. --- cut here --- The mechanism kgdb uses to quiesce other CPUs means other CPUs cannot be in irqsave critical sections. ------------------------------------------------------------------------------ Is your legacy SCM system holding you back? Join Perforce May 7 to find out: • 3 signs your SCM is hindering your productivity • Requirements for releasing software faster • Expert tips and advice for migrating your SCM now http://p.sf.net/sfu/perforce _______________________________________________ Kgdb-bugreport mailing list Kgdb-bugreport@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kgdb-bugreport
