diff options
Diffstat (limited to 'Notes')
| -rw-r--r-- | Notes | 49 |
1 files changed, 38 insertions, 11 deletions
@@ -85,17 +85,44 @@ test pipe reader closes then write test two readers, two writers. test children being inherited by grandparent &c -kill - sleep()ing for something - running at user level - running in kernel - ooh, the relevant CPU may never get a clock interrupt - should each cpu have its own clock? - where to check? - loops around sleep() - return from any trap - rules about being killed deep inside a system call - test above cases +some sleep()s should be interruptible by kill() cli/sti in acquire/release should nest! in case you acquire two locks + +what would need fixing if we got rid of kernel_lock? + console output + proc_exit() needs lock on proc *array* to deallocate + kill() needs lock on proc *array* + allocator's free list + global fd table (really free-ness) + sys_close() on fd table + fork on proc list, also next pid + hold lock until public slots in proc struct initialized + +locks + init_lock + sequences CPU startup + proc_table_lock + also protects next_pid + per-fd lock *just* protects count read-modify-write + also maybe freeness? + memory allocator + printf + +wakeup needs proc_table_lock + so we need recursive locks? + or you must hold the lock to call wakeup? + +if locks contain proc *, they can't be used at interrupt time + only proc_table_lock will be used at interrupt time? + maybe it doesn't matter if we use curproc? + +in general, the table locks protect both free-ness and + public variables of table elements + in many cases you can use table elements w/o a lock + e.g. if you are the process, or you are using an fd + +why can't i get a lock in console code? + always triple fault +lock code shouldn't call cprintf... |