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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>
This commit is contained in:
Oleg Nesterov 2012-11-23 20:15:17 +01:00
parent 04aab9b200
commit 9a98e03cc1
1 changed files with 13 additions and 18 deletions
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31
kernel/events/uprobes.c
View File

@ -482,16 +482,12 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
up_read(&uprobe->consumer_rwsem);
}
/* Returns the previous consumer */
static struct uprobe_consumer *
consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
{
down_write(&uprobe->consumer_rwsem);
uc->next = uprobe->consumers;
uprobe->consumers = uc;
up_write(&uprobe->consumer_rwsem);
return uc->next;
}
/*
@ -820,9 +816,15 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register)
return err;
}
static int __uprobe_register(struct uprobe *uprobe)
static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)
{
return register_for_each_vma(uprobe, true);
int err;
consumer_add(uprobe, uc);
err = register_for_each_vma(uprobe, true);
if (!err) /* TODO: pointless unless the first consumer */
set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
return err;
}
static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
@ -867,21 +869,14 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *
if (offset > i_size_read(inode))
return -EINVAL;
ret = 0;
ret = -ENOMEM;
mutex_lock(uprobes_hash(inode));
uprobe = alloc_uprobe(inode, offset);
if (!uprobe) {
ret = -ENOMEM;
} else if (!consumer_add(uprobe, uc)) {
ret = __uprobe_register(uprobe);
if (ret) {
if (uprobe) {
ret = __uprobe_register(uprobe, uc);
if (ret)
__uprobe_unregister(uprobe, uc);
} else {
set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
}
}
mutex_unlock(uprobes_hash(inode));
if (uprobe)
put_uprobe(uprobe);