Messages in this thread |  | | Date | Wed, 28 Mar 2018 11:03:33 -0400 (EDT) | From | Mathieu Desnoyers <> | Subject | Re: [RFC PATCH for 4.17 02/21] rseq: Introduce restartable sequences system call (v12) |
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----- On Mar 28, 2018, at 8:52 AM, Peter Zijlstra peterz@infradead.org wrote:
> On Wed, Mar 28, 2018 at 02:29:46PM +0200, Peter Zijlstra wrote: >> > +static int rseq_get_rseq_cs(struct task_struct *t, >> > + unsigned long *start_ip, >> > + unsigned long *post_commit_offset, >> > + unsigned long *abort_ip, >> > + uint32_t *cs_flags) >> > +{ > >> >> > + >> > + *cs_flags = rseq_cs.flags; >> > + *start_ip = rseq_cs.start_ip; >> > + *post_commit_offset = rseq_cs.post_commit_offset; >> > + *abort_ip = rseq_cs.abort_ip; >> >> Then this becomes a straight struct assignment. > > I initially suggested passing a structure instead of many arguments, but > then recondidered, mostly because it will be inlined (due to having only > the one caller) anyway. Still, maybe a struct will work better, I dunno.
I find the result of struct pointer argument cleaner indeed. I'll go for that approach.
I'll memset rseq_cs to 0 in the following case though, because the caller expects the content of the structure to be set when rseq_get_rseq_cs() succeeds.
static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs) { struct rseq_cs __user *urseq_cs; unsigned long ptr; u32 __user *usig; u32 sig; int ret;
ret = __get_user(ptr, &t->rseq->rseq_cs); if (ret) return ret; if (!ptr) { memset(rseq_cs, 0, sizeof(*rseq_cs)); return 0; }
[...]
Thanks!
Mathieu
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
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