On Wed, Feb 12, 2020 at 2:41 AM Horia Geanta <horia.geanta@xxxxxxx> wrote:
>
> On 1/27/2020 6:57 PM, Andrey Smirnov wrote:
> > @@ -60,12 +65,12 @@ static struct caam_rng_ctx *to_caam_rng_ctx(struct hwrng *r)
> > static void caam_rng_done(struct device *jrdev, u32 *desc, u32 err,
> > void *context)
> > {
> > - struct completion *done = context;
> > + struct caam_rng_job_ctx *jctx = context;
> >
> > if (err)
> > - caam_jr_strstatus(jrdev, err);
> > + *jctx->err = caam_jr_strstatus(jrdev, err);
> >
> > - complete(done);
> > + complete(jctx->done);
> > }
> >
> > static u32 *caam_init_desc(u32 *desc, dma_addr_t dst_dma, int len)
> > @@ -89,6 +94,10 @@ static int caam_rng_read_one(struct device *jrdev,
> > {
> > dma_addr_t dst_dma;
> > int err;
> > + struct caam_rng_job_ctx jctx = {
> > + .done = done,
> > + .err = &err,
> > + };
> >
> > len = min_t(int, len, CAAM_RNG_MAX_FIFO_STORE_SIZE);
> >
> > @@ -101,7 +110,7 @@ static int caam_rng_read_one(struct device *jrdev,
> > init_completion(done);
> > err = caam_jr_enqueue(jrdev,
> > caam_init_desc(desc, dst_dma, len),
> > - caam_rng_done, done);
> > + caam_rng_done, &jctx);
> AFAICT there's a race condition b/w caam_jr_enqueue() and caam_rng_done(),
> both writing to "err":
> caam_jr_enqueue()
> -> JR interrupt -> caam_jr_interrupt() -> tasklet_schedule()...
> -> spin_unlock_bh()
> -> caam_jr_dequeue() -> caam_rng_done() -> write err
> -> return 0 -> write err
>
Yes, I thought it didn't really matter for calling
wait_for_completion(done), but now that I think on it again, it can
return wrong result code from vcaam_rng_read_one(). Will fix in v8.
Thanks,
Andrey Smirnov
