Changes between Version 114 and Version 115 of processus_thread


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Timestamp:
Nov 3, 2019, 2:25:23 PM (3 years ago)
Author:
alain
Comment:

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  • processus_thread

    v114 v115  
    148148This destruction mechanism can involve three threads: the target thread T, the killer thread K, and the joining thread J:
    149149
    150 It uses two specific fields in the target thread descriptor: the ''join_lock'' field is a remote_spin_lock, and the ''join_xp'' field contains an extended pointer on the first arrived thread. It uses also two specific [https://www-soc.lip6.fr/trac/almos-mkh/browser/trunk/kernel/kern/thread.h#L72 THREAD_FLAG_JOIN_DONE] and [https://www-soc.lip6.fr/trac/almos-mkh/browser/trunk/kernel/kern/thread.h#L73 THREAD_FLAG_KILL_DONE] flags in the target thread descriptor ''flags'' field, and one specific blocking bit [https://www-soc.lip6.fr/trac/almos-mkh/browser/trunk/kernel/kern/thread.h#L86 THREAD_BLOCKED_JOIN], in the ''blocked'' field.
    151 
    152  * Both the killer thread K, executing the thread_kill() function), and the joining thread J, executing the sys_thread_join() function, try to take the ''join_lock'' implemented in the T thread descriptor (the ''join_lock'' in the J thread is not used).
     150It uses three specific fields in the target thread descriptor:
     151 * the ''join_lock'' field is a remote_spin_lock.
     152 * the ''join_xp'' field contains an extended pointer on the first arrived thread.
     153 * the ''exit_status'' field is used to transmit the global pointer returned by the terminating thread to the joining thread.
     154It uses also two specific [https://www-soc.lip6.fr/trac/almos-mkh/browser/trunk/kernel/kern/thread.h#L72 THREAD_FLAG_JOIN_DONE] and [https://www-soc.lip6.fr/trac/almos-mkh/browser/trunk/kernel/kern/thread.h#L73 THREAD_FLAG_KILL_DONE] flags in the target thread descriptor ''flags'' field, and one specific blocking bit [https://www-soc.lip6.fr/trac/almos-mkh/browser/trunk/kernel/kern/thread.h#L86 THREAD_BLOCKED_JOIN], in the ''blocked'' field.
     155
     156 * Both the killer thread K, (executing the thread_kill() or the thread_exit() function), and the joining thread J (executing the sys_thread_join() function), try to take the ''join_lock'' implemented in the T thread descriptor (the ''join_lock'' in the J thread is not used).
    153157 * The K thread test the FLAG_JOIN_DONE in the T thread descriptor:
    154    * If the FLAG_JOIN_DONE is set, the J thread arrived first and is blocked on the BLOCKED_JOIN condition: the K thread unblocks the J thread from the BLOCKED_JOIN condition (using the ''join_xp'' field in the T thread), reset the JOIN_DONE flag in T thread, releases the ''join_lock'' in T thread, and completes the T thread destruction as described in the detached case.
    155    * If the FLAG_JOIN_DONE is not set, the K thread arrived first: the K thread blocks the K thread on the BLOCKED_JOIN condition, sets the FLAG_KILL_DONE in the T thread, registers the killer thread extended pointer in the T thread ''join_xp'' field, releases the ''join_lock'' in the T thread, and deschedules. It completes the T thread destruction as described in the detached case when it is unblocked by the J thread.
     158   * If the FLAG_JOIN_DONE is set, the J thread arrived first and is blocked on the BLOCKED_JOIN condition: the K thread unblocks the J thread from the BLOCKED_JOIN condition (using the ''join_xp'' field in the T thread), reset the JOIN_DONE flag in T thread,  registers the exit status in the T thread ''exit_status'' field (only when the K thread is the T pthread itself executing the pthread_exit() function, and finally  releases the ''join_lock'' in T thread. It completes the T thread destruction as described in the detached case.
     159   * If the FLAG_JOIN_DONE is not set, the K thread arrived first: the K thread blocks the K thread on the BLOCKED_JOIN condition, sets the FLAG_KILL_DONE in the T thread, registers the exit status in the T thread ''exit_status'' field (only when the K thread is the T pthread itself executing the pthread_exit() function, registers the killer thread extended pointer in the T thread ''join_xp'' field, releases the ''join_lock'' in the T thread, and deschedules. It completes the T thread destruction as described in the detached case when it is unblocked by the J thread.
    156160 * The J thread tests the FLAG_KILL_DONE in the T thread descriptor:
    157161   * If the FLAG_KILL_DONE is set, the K thread arrived first and is blocked on the BLOCKED_JOIN condition: the J thread unblocks the killer thread, resets the FLAG_KILL_DONE in the T thread, releases the "join_lock" in T thread, and returns.