Messages in this thread Patch in this message |  | | | Date | Fri, 11 Nov 2005 00:27:11 +0100 | | From | Christoph Hellwig <> | | Subject | Re: [PATCH] use ptrace_get_task_struct in various places |
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On Mon, Nov 07, 2005 at 10:11:49PM -0800, Andrew Morton wrote: > Christoph Hellwig <hch@lst.de> wrote: > > > > The ptrace_get_task_struct() helper that I added as part of the ptrace > > consolidation is usefull in variety of places that currently opencode > > it. Switch them to the common helper. > > If we're going to export ptrace_get_task_struct() to the world it would be > nice to document it too - things like returning zero and a NULL *childp is > a little obscure.
done, patch below.
> In arch/ia64/ia32/sys_ia32.c this patch will cause PTRACE_TRACEME requests > to be handled by ptrace_request()
you mean ptrace_get_task_struct?
> rather than by sys_ptrace(), which is a > not-obviously-correct change.
sys_ptrace has the same code for it, in fact just about every ptrace implementation uses ptrace_get_task_struct to handle that code, but ptrace_get_task_struct can't be used by ia64 because some oddness in the !PTRACE_TRACEME codepath.
> Was the omission of arch/ia64/kernel/ptrace.c:sys_ptrace() deliberate?
yes. it has some oddness about finding the 'right' task_struct of a multi-threaded process.
Index: linux-2.6/kernel/ptrace.c =================================================================== --- linux-2.6.orig/kernel/ptrace.c 2005-11-10 15:36:12.000000000 +0100 +++ linux-2.6/kernel/ptrace.c 2005-11-10 15:46:05.000000000 +0100 @@ -407,6 +407,23 @@ return ret; } +/** + * ptrace_get_task_struct -- grab a task struct reference for ptrace + * @long: ptrace request type + * @pid: process to work on + * @childp: task struct returned + * + * This function is a helper for ptrace implementations. It checks + * permissions and then grabs a task struct for use of the actual + * ptrace implementation. As a special case also handles PTRACE_TRACEME + * completely (as it's trivial and doesn't need a task_struct reference. + * + * The calling convention is a little bit odd: negative return value + * means failure, positive one sucess. But even when this function + * suceeds @childp can be NULL and the calling ptrace implementation + * should return sucessfully immediately afterwards. This is to support + * the PTRACE_TRACEME special case. + */ int ptrace_get_task_struct(long request, long pid, struct task_struct **childp) { struct task_struct *child; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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