Messages in this thread | | | From | Roland McGrath <> | Subject | Re: [PATCH 2/2] posix-cpu-timers: use ->sighand instead of ->signal to check the task is alive | Date | Wed, 4 Feb 2009 19:31:20 -0800 (PST) |
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> It doesn't matter which pointer to check under tasklist to ensure the task > was not released, ->signal or ->sighand. But we are going to make ->signal > refcountable, change the code to use ->sighand.
I haven't been following what that's about (signal_struct already has two atomic counts!). Uses here protecting cpu_clock_sample_group() e.g., are around looking at ->signal->foobar, so if ->signal is still there, why not look at it and be able to get the sample in whatever small window this is?
I don't really understand what this new case might mean though. Most things that look at ->signal need to lock it, so access doesn't make any sense if there is no siglock because ->sighand is clear while ->signal is not.
Thanks, Roland
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