dmaengine: at_hdmac: Return err in case the chan is not free at alloc res time

Having a list of descriptors allocated for the channel at
device_alloc_chan_resources() time is a sign for bad free usage.
Return err and add a debug message in case the channel is not
free from a previous use.

atchan->descs_allocated becomes useless, get rid of it. More,
drop the error message in atc_desc_get() because now it would
introduce an extra if statement. The callers of atc_desc_get()
already print error messages in case the callee fails, no one
is hurt.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Link: https://lore.kernel.org/r/20200123140237.125799-3-tudor.ambarus@microchip.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 301bae45cf8d0dbc9372868e7e43d96e4453ffcc..e17b75075904f7bba976da0c27842f4f850e8993 100644 (file)
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -146,17 +146,8 @@ static struct at_desc *atc_desc_get(struct at_dma_chan *atchan)
                "scanned %u descriptors on freelist\n", i);
 
        /* no more descriptor available in initial pool: create one more */
-       if (!ret) {
+       if (!ret)
                ret = atc_alloc_descriptor(&atchan->chan_common, GFP_ATOMIC);
-               if (ret) {
-                       spin_lock_irqsave(&atchan->lock, flags);
-                       atchan->descs_allocated++;
-                       spin_unlock_irqrestore(&atchan->lock, flags);
-               } else {
-                       dev_err(chan2dev(&atchan->chan_common),
-                                       "not enough descriptors available\n");
-               }
-       }
 
        return ret;
 }
@@ -1553,6 +1544,11 @@ static int atc_alloc_chan_resources(struct dma_chan *chan)
                return -EIO;
        }
 
+       if (!list_empty(&atchan->free_list)) {
+               dev_dbg(chan2dev(chan), "can't allocate channel resources (channel not freed from a previous use)\n");
+               return -EIO;
+       }
+
        cfg = ATC_DEFAULT_CFG;
 
        atslave = chan->private;
@@ -1568,11 +1564,6 @@ static int atc_alloc_chan_resources(struct dma_chan *chan)
                        cfg = atslave->cfg;
        }
 
-       /* have we already been set up?
-        * reconfigure channel but no need to reallocate descriptors */
-       if (!list_empty(&atchan->free_list))
-               return atchan->descs_allocated;
-
        /* Allocate initial pool of descriptors */
        for (i = 0; i < init_nr_desc_per_channel; i++) {
                desc = atc_alloc_descriptor(chan, GFP_KERNEL);
@@ -1584,17 +1575,15 @@ static int atc_alloc_chan_resources(struct dma_chan *chan)
                list_add_tail(&desc->desc_node, &atchan->free_list);
        }
 
-       atchan->descs_allocated = i;
        dma_cookie_init(chan);
 
        /* channel parameters */
        channel_writel(atchan, CFG, cfg);
 
        dev_dbg(chan2dev(chan),
-               "alloc_chan_resources: allocated %d descriptors\n",
-               atchan->descs_allocated);
+               "alloc_chan_resources: allocated %d descriptors\n", i);
 
-       return atchan->descs_allocated;
+       return i;
 }
 
 /**
@@ -1608,9 +1597,6 @@ static void atc_free_chan_resources(struct dma_chan *chan)
        struct at_desc          *desc, *_desc;
        LIST_HEAD(list);
 
-       dev_dbg(chan2dev(chan), "free_chan_resources: (descs allocated=%u)\n",
-               atchan->descs_allocated);
-
        /* ASSERT:  channel is idle */
        BUG_ON(!list_empty(&atchan->active_list));
        BUG_ON(!list_empty(&atchan->queue));
@@ -1623,7 +1609,6 @@ static void atc_free_chan_resources(struct dma_chan *chan)
                dma_pool_free(atdma->dma_desc_pool, desc, desc->txd.phys);
        }
        list_splice_init(&atchan->free_list, &list);
-       atchan->descs_allocated = 0;
        atchan->status = 0;
 
        /*

diff --git a/drivers/dma/at_hdmac_regs.h b/drivers/dma/at_hdmac_regs.h
index fe8a5853ec491b321f8eff6d6990bf1f72943dbb..397692e937b31b781918d8881a48afc924d0c442 100644 (file)
--- a/drivers/dma/at_hdmac_regs.h
+++ b/drivers/dma/at_hdmac_regs.h
@@ -243,7 +243,6 @@ enum atc_status {
  * @active_list: list of descriptors dmaengine is being running on
  * @queue: list of descriptors ready to be submitted to engine
  * @free_list: list of descriptors usable by the channel
- * @descs_allocated: records the actual size of the descriptor pool
  */
 struct at_dma_chan {
        struct dma_chan         chan_common;
@@ -264,7 +263,6 @@ struct at_dma_chan {
        struct list_head        active_list;
        struct list_head        queue;
        struct list_head        free_list;
-       unsigned int            descs_allocated;
 };
 
 #define        channel_readl(atchan, name) \