Re: [PATCH 06/12] net/rtdev: ensure per-device skbs get mapped at registration

[Jan Kiszka via Xenomai]

On 24.01.19 16:34, Philippe Gerum wrote:
This patch works around a regression introduced by #74464ee37d0,
causing a new device's skbs not to be passed to its ->map_rtskb()
handler when registered, breaking further DMA inits in the driver.
Signed-off-by: Philippe Gerum <r...@xenomai.org>
---
  kernel/drivers/net/stack/rtdev.c | 37 +++++++++++++++++++++++---------
  1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/kernel/drivers/net/stack/rtdev.c b/kernel/drivers/net/stack/rtdev.c
index 631ca1804..286d08cb1 100644
--- a/kernel/drivers/net/stack/rtdev.c
+++ b/kernel/drivers/net/stack/rtdev.c
@@ -45,6 +45,7 @@ struct rtnet_device         *rtnet_devices[MAX_RT_DEVICES];
  static struct rtnet_device  *loopback_device;
  static DEFINE_RTDM_LOCK(rtnet_devices_rt_lock);
  static LIST_HEAD(rtskb_mapped_list);
+static LIST_HEAD(rtskb_mapwait_list);
  
  LIST_HEAD(event_hook_list);
  DEFINE_MUTEX(rtnet_devices_nrt_lock);
@@ -459,8 +460,12 @@ int rtdev_map_rtskb(struct rtskb *skb)
        }
      }
  
-    if (!err && skb->buf_dma_addr != RTSKB_UNMAPPED)
-       list_add(&skb->entry, &rtskb_mapped_list);
+    if (!err) {
+           if (skb->buf_dma_addr != RTSKB_UNMAPPED)
+                   list_add(&skb->entry, &rtskb_mapped_list);
+           else
+                   list_add(&skb->entry, &rtskb_mapwait_list);
+    }
  
      mutex_unlock(&rtnet_devices_nrt_lock);
  
@@ -471,19 +476,31 @@ int rtdev_map_rtskb(struct rtskb *skb)
  
  static int rtdev_map_all_rtskbs(struct rtnet_device *rtdev)
  {
-    struct rtskb *skb;
-    int err = 0;
+    struct rtskb *skb, *n;
+    int err;
  
      if (!rtdev->map_rtskb)
-       return 0;
+           return 0;
  
-    list_for_each_entry(skb, &rtskb_mapped_list, entry) {
-       err = rtskb_map(rtdev, skb);
-       if (err)
-          break;
+    if (!list_empty(&rtskb_mapped_list)) {

Why this extra check? list_for_each_entry should just do nothing if the list is 
empty.

+           list_for_each_entry(skb, &rtskb_mapped_list, entry) {
+                   err = rtskb_map(rtdev, skb);
+                   if (err)
+                           return err;
+           }
      }
  
-    return err;
+    if (!list_empty(&rtskb_mapwait_list)) {

Same here.

+           list_for_each_entry_safe(skb, n, &rtskb_mapwait_list, entry) {
+                   err = rtskb_map(rtdev, skb);
+                   if (err)
+                           return err;
+                   list_del(&skb->entry);
+                   list_add(&skb->entry, &rtskb_mapped_list);
+           }
+    }
+
+    return 0;
  }
  
  


Style mix: Eventually, we should switch all RTnet code to kernel style. For now, 
we have 4-space-indention, and we should keep it until then. Mixing things will 
only make it more messy.

Jan

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