uprobes: _register() should always do register_for_each_vma(true)
To support the filtering uprobe_register() should do register_for_each_vma(true) every time the new consumer comes, we need to install the previously nacked breakpoints. Note: - uprobes_mutex[] should die, what it actually protects is alloc_uprobe(). - UPROBE_RUN_HANDLER should die too, obviously it can't work unless uprobe has a single consumer. The consumer should serialize with _register/_unregister itself. Or this flag should live in uprobe_consumer->state. - Perhaps we can do some optimizations later. For example, if filter_chain() never returns false uprobe can record this fact and avoid the unnecessary register_for_each_vma(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
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@ -482,16 +482,12 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
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up_read(&uprobe->consumer_rwsem);
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}
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/* Returns the previous consumer */
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static struct uprobe_consumer *
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consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
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static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
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{
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down_write(&uprobe->consumer_rwsem);
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uc->next = uprobe->consumers;
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uprobe->consumers = uc;
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up_write(&uprobe->consumer_rwsem);
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return uc->next;
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}
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/*
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@ -820,9 +816,15 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register)
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return err;
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}
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static int __uprobe_register(struct uprobe *uprobe)
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static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)
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{
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return register_for_each_vma(uprobe, true);
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int err;
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consumer_add(uprobe, uc);
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err = register_for_each_vma(uprobe, true);
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if (!err) /* TODO: pointless unless the first consumer */
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set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
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return err;
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}
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static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
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@ -867,21 +869,14 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *
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if (offset > i_size_read(inode))
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return -EINVAL;
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ret = 0;
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ret = -ENOMEM;
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mutex_lock(uprobes_hash(inode));
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uprobe = alloc_uprobe(inode, offset);
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if (!uprobe) {
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ret = -ENOMEM;
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} else if (!consumer_add(uprobe, uc)) {
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ret = __uprobe_register(uprobe);
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if (ret) {
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if (uprobe) {
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ret = __uprobe_register(uprobe, uc);
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if (ret)
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__uprobe_unregister(uprobe, uc);
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} else {
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set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
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}
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}
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mutex_unlock(uprobes_hash(inode));
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if (uprobe)
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put_uprobe(uprobe);
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