Messages in this thread | | | From | Roland McGrath <> | Subject | Re: [PATCH -mm 3/3] proc: make task_sig() lockless | Date | Mon, 12 Apr 2010 23:30:13 -0700 (PDT) |
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> Yes, /proc/pid/status can report the intermediate state, I even sent > the updated changelog to document this. > > But if you are not sure this is OK, I am worried. Do you think we should > drop this patch? If yes, I won't argue.
I'm not dead-set against it, but I am hesitant. My inclination is not to remove any previous userland atomicity guarantees with regard to observable signal state in any form. At least, don't do that in part of a whole cleanup flurry where it is intermixed with lots of changes that really are pure cleanup with absolutely no userland-observable change. If it really helps to fragment what was atomic before, then we can consider it. But let's not be in a hurry.
David mentioned that users who do multiple reads due to using tiny buffers already don't get atomic sampling. That is certainly true but I don't think it's relevant. It is completely reliable that you can easily allocate a buffer big enough to get all the Sig* fields on the first read, and any user program that might care about the coherence of the data, by definition, is already doing that.
Thanks, Roland
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