Messages in this thread | | | Subject | Re: [RFC] [PATCH 2.6.37-rc5-tip 8/20] 8: uprobes: mmap and fork hooks. | From | Peter Zijlstra <> | Date | Wed, 26 Jan 2011 11:20:39 +0100 |
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On Wed, 2011-01-26 at 14:33 +0530, Srikar Dronamraju wrote: > > > I actually dont like to release the write_lock and then reacquire it. > write_opcode, which is called thro install_uprobe, i.e to insert the > actual breakpoint instruction takes a read lock on the mmap_sem. > Hence uprobe_mmap gets called in context with write lock on mmap_sem > held, I had to release it before calling install_uprobe.
Ah, right, so that's going to give you a head-ache ;-)
The moment you release this mmap_sem, the map you're going to install the probe point in can go away.
The only way to make this work seems to start by holding the mmap_sem for writing and make a breakpoint install function that assumes its taken and doesn't try to acquire it again.
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