Re: [RFC] [PATCH 0/7] UBP, XOL and Uprobes [ Summary of Comments and actions to be taken ]

[Ananth N Mavinakayanahalli <ananth@in.ibm.com>]

On Fri, Jan 22, 2010 at 12:32:32PM +0530, Srikar Dronamraju wrote:
> Here is a summary of the Comments and actions that need to be taken for
> the current uprobes patchset. Please let me know if I missed or
> misunderstood any of your comments.  
> 
> 1. Uprobes depends on trap signal.
> 	Uprobes depends on trap signal rather than hooking to the global
> die notifier. It was suggested that we hook to the global die notifier.
> 
> 	In the next version of patches, Uprobes will use the global die
> 	notifier and look at the per-task count of the probes in use to
> 	see if it has to be consumed.
> 
> 	However this would reduce the ability of uprobe handlers to
> 	sleep. Since we are dealing with userspace, sleeping in handlers
> 	would have been a good feature. We are looking at ways to get
> 	around this limitation.

We could set a TIF_ flag in the notifier to indicate a breakpoint hit
and process it in task context before the task heads into userspace.

Ananth