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    SubjectRe: [PATCH v7 6/9] crypto: caam - check if RNG job failed
    Date
    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

    Horia

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