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Opened 10 years ago

Closed 10 years ago

#244 closed defect (fixed)

Exiting thread causes Udebug begin to block forever

Reported by: Jiri Svoboda Owned by: Jiri Svoboda
Priority: major Milestone: 0.4.3
Component: helenos/unspecified Version: mainline
Keywords: Cc:
Blocker for: Depends on:
See also:

Description

Tomas Brambora noticed that if task creates a thread, this thread exits and then we try to open a debugging session with the task, Udebug begin method will block forever.

Change History (2)

comment:1 Changed 10 years ago by Jiri Svoboda

It would appear that the handling of stoppability/not_stoppable_count at the entry and exit of a thread have problems stemming from code evolution (historically a thread was stoppable at entry and exit, now it is not).

What is observed: A userspace thread starts with not_stoppable_count contribution of zero. Then in uinit it gets +1. In thread_exit() it has still +1 and this stays so until the thread is destroyed. So +1 is leaked into not_stoppable_count.

Need to revisit stoppability/not_stoppable_count handling during thread creation, uspace initialization and thread termination.

comment:2 Changed 10 years ago by Jiri Svoboda

Resolution: fixed
Status: newclosed

Fixed in changeset:head,511. In the end the only problem was that we did not make the userspace thread stoppable before it would exit. This makes the not_stoppable_count balance of both kernel and userspace threads zero when they exit. Also note that is is okay to mark an exiting thread stoppable according to definition.

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