Messages in this thread | | | Date | Sat, 12 Sep 2009 10:19:30 -0700 | From | Sukadev Bhattiprolu <> | Subject | Re: [RFC][v6][PATCH 0/9] clone_with_pids() syscall |
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Peter Zijlstra [peterz@infradead.org] wrote: | On Fri, 2009-09-11 at 09:47 -0700, Sukadev Bhattiprolu wrote: | > | Also, if you're passing a struct, why not put nr_pids in there, and | > | replace clone_pid_struct with a simple array? That would give us | > | | > | struct clone_struct { | > | u64 flags; | > | u64 child_stack; | > | u32 child_tid; | > | u32 parent_tid;
BTW, these two tids are __user pointers that kernel copies data into. They should be u64 to avoid conversions in architecture specific code ?
| > | u32 nr_pids; | > | u32 reserved1; | > | u64 reserved2; | > | }; | > | | > | int clone2(struct clone_struct *cs, pid_t *pids); | > | > My only concern with this approach was the extra copy_from_user() in the | > common case (i.e when not using the extended features). I assume the | > overhead of copy_from_user() is small enough to be ignored ? | | I would think so, esp for small structure, it would be a cache hot copy. | That is, for x86 I doubt it'll show up. No idea what hoops other arch | have to jump through to get copy_from_user() doing what it does.
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