From: Oleg Nesterov Date: Sat, 29 Dec 2012 16:49:11 +0000 (+0100) Subject: uprobes: Teach handler_chain() to filter out the probed task X-Git-Tag: v3.9-rc1~173^2~2^2~22 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=da1816b1caeccdff04531e763bb35d7caa3ed19f;p=pandora-kernel.git uprobes: Teach handler_chain() to filter out the probed task Currrently the are 2 problems with pre-filtering: 1. It is not possible to add/remove a task (mm) after uprobe_register() 2. A forked child inherits all breakpoints and uprobe_consumer can not control this. This patch does the first step to improve the filtering. handler_chain() removes the breakpoints installed by this uprobe from current->mm if all handlers return UPROBE_HANDLER_REMOVE. Note that handler_chain() relies on ->register_rwsem to avoid the race with uprobe_register/unregister which can add/del a consumer, or even remove and then insert the new uprobe at the same address. Perhaps we will add uprobe_apply_mm(uprobe, mm, is_register) and teach copy_mm() to do filter(UPROBE_FILTER_FORK), but I think this change makes sense anyway. Note: instead of checking the retcode from uc->handler, we could add uc->filter(UPROBE_FILTER_BPHIT). But I think this is not optimal to call 2 hooks in a row. This buys nothing, and if handler/filter do something nontrivial they will probably do the same work twice. Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju --- Reading git-diff-tree failed