crypto: omap-sham - replace flags operation with atomic bit operations
Dmitry Kasatkin [Thu, 2 Jun 2011 18:10:06 +0000 (21:10 +0300)]
Some flags are changed in interrupt handlers and verified in the tasklet.
There might be a race condition when tasklet is interrupted or another
cpu/core will run IRQ handler and tasklet in parallel.
Atomic bitops functions are now used instead of bitmask operations.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@nokia.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/omap-sham.c

index 64698ad..208404e 100644 (file)
@@ -240,7 +240,7 @@ static int omap_sham_hw_init(struct omap_sham_dev *dd)
 {
        clk_enable(dd->iclk);
 
-       if (!(dd->flags & BIT(FLAGS_INIT))) {
+       if (!test_bit(FLAGS_INIT, &dd->flags)) {
                omap_sham_write_mask(dd, SHA_REG_MASK,
                        SHA_REG_MASK_SOFTRESET, SHA_REG_MASK_SOFTRESET);
 
@@ -248,7 +248,7 @@ static int omap_sham_hw_init(struct omap_sham_dev *dd)
                                        SHA_REG_SYSSTATUS_RESETDONE))
                        return -ETIMEDOUT;
 
-               dd->flags |= BIT(FLAGS_INIT);
+               set_bit(FLAGS_INIT, &dd->flags);
                dd->err = 0;
        }
 
@@ -303,7 +303,7 @@ static int omap_sham_xmit_cpu(struct omap_sham_dev *dd, const u8 *buf,
                return -ETIMEDOUT;
 
        if (final)
-               ctx->flags |= BIT(FLAGS_FINAL); /* catch last interrupt */
+               set_bit(FLAGS_FINAL, &ctx->flags); /* catch last interrupt */
 
        len32 = DIV_ROUND_UP(length, sizeof(u32));
 
@@ -336,9 +336,9 @@ static int omap_sham_xmit_dma(struct omap_sham_dev *dd, dma_addr_t dma_addr,
        ctx->digcnt += length;
 
        if (final)
-               ctx->flags |= BIT(FLAGS_FINAL); /* catch last interrupt */
+               set_bit(FLAGS_FINAL, &ctx->flags); /* catch last interrupt */
 
-       dd->flags |= BIT(FLAGS_DMA_ACTIVE);
+       set_bit(FLAGS_DMA_ACTIVE, &dd->flags);
 
        omap_start_dma(dd->dma_lch);
 
@@ -642,7 +642,7 @@ static void omap_sham_finish_req(struct ahash_request *req, int err)
 
        if (!err) {
                omap_sham_copy_hash(req, 1);
-               if (ctx->flags & BIT(FLAGS_FINAL))
+               if (test_bit(FLAGS_FINAL, &ctx->flags))
                        err = omap_sham_finish(req);
        } else {
                ctx->flags |= BIT(FLAGS_ERROR);
@@ -666,14 +666,14 @@ static int omap_sham_handle_queue(struct omap_sham_dev *dd,
        spin_lock_irqsave(&dd->lock, flags);
        if (req)
                ret = ahash_enqueue_request(&dd->queue, req);
-       if (dd->flags & BIT(FLAGS_BUSY)) {
+       if (test_bit(FLAGS_BUSY, &dd->flags)) {
                spin_unlock_irqrestore(&dd->lock, flags);
                return ret;
        }
        backlog = crypto_get_backlog(&dd->queue);
        async_req = crypto_dequeue_request(&dd->queue);
        if (async_req)
-               dd->flags |= BIT(FLAGS_BUSY);
+               set_bit(FLAGS_BUSY, &dd->flags);
        spin_unlock_irqrestore(&dd->lock, flags);
 
        if (!async_req)
@@ -1037,13 +1037,10 @@ static void omap_sham_done_task(unsigned long data)
        struct omap_sham_reqctx *ctx = ahash_request_ctx(req);
        int ready = 0, err = 0;
 
-       if (ctx->flags & BIT(FLAGS_OUTPUT_READY)) {
-               ctx->flags &= ~BIT(FLAGS_OUTPUT_READY);
+       if (test_and_clear_bit(FLAGS_OUTPUT_READY, &ctx->flags))
                ready = 1;
-       }
 
-       if (dd->flags & BIT(FLAGS_DMA_ACTIVE)) {
-               dd->flags &= ~BIT(FLAGS_DMA_ACTIVE);
+       if (test_and_clear_bit(FLAGS_DMA_ACTIVE, &dd->flags)) {
                omap_sham_update_dma_stop(dd);
                if (!dd->err)
                        err = omap_sham_update_dma_start(dd);
@@ -1077,7 +1074,7 @@ static irqreturn_t omap_sham_irq(int irq, void *dev_id)
                return IRQ_HANDLED;
        }
 
-       if (unlikely(ctx->flags & BIT(FLAGS_FINAL)))
+       if (unlikely(test_bit(FLAGS_FINAL, &ctx->flags)))
                /* final -> allow device to go to power-saving mode */
                omap_sham_write_mask(dd, SHA_REG_CTRL, 0, SHA_REG_CTRL_LENGTH);
 
@@ -1085,7 +1082,7 @@ static irqreturn_t omap_sham_irq(int irq, void *dev_id)
                                 SHA_REG_CTRL_OUTPUT_READY);
        omap_sham_read(dd, SHA_REG_CTRL);
 
-       ctx->flags |= BIT(FLAGS_OUTPUT_READY);
+       set_bit(FLAGS_OUTPUT_READY, &ctx->flags);
        dd->err = 0;
        tasklet_schedule(&dd->done_task);
 
@@ -1099,7 +1096,7 @@ static void omap_sham_dma_callback(int lch, u16 ch_status, void *data)
        if (ch_status != OMAP_DMA_BLOCK_IRQ) {
                pr_err("omap-sham DMA error status: 0x%hx\n", ch_status);
                dd->err = -EIO;
-               dd->flags &= ~BIT(FLAGS_INIT); /* request to re-initialize */
+               clear_bit(FLAGS_INIT, &dd->flags);/* request to re-initialize */
        }
 
        tasklet_schedule(&dd->done_task);