samples/bpf: xdp_monitor use err code from tracepoint xdp:xdp_devmap_xmit

Update xdp_monitor to use the recently added err code introduced
in tracepoint xdp:xdp_devmap_xmit, to show if the drop count is
caused by some driver general delivery problem.  Other kind of drops
will likely just be more normal TX space issues.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 40 insertions, 5 deletions

diff --git a/samples/bpf/xdp_monitor_kern.c b/samples/bpf/xdp_monitor_kern.c
index 2854aa0665ea..ad10fe700d7d 100644
--- a/samples/bpf/xdp_monitor_kern.c
+++ b/samples/bpf/xdp_monitor_kern.c
@@ -125,6 +125,7 @@ struct datarec {
         u64 processed;
         u64 dropped;
         u64 info;
+        u64 err;
 };
 #define MAX_CPUS 64
 
@@ -228,6 +229,7 @@ struct devmap_xmit_ctx {
         int sent;               //      offset:24; size:4; signed:1;
         int from_ifindex;       //      offset:28; size:4; signed:1;
         int to_ifindex;         //      offset:32; size:4; signed:1;
+        int err;                //      offset:36; size:4; signed:1;
 };
 
 SEC("tracepoint/xdp/xdp_devmap_xmit")
@@ -245,5 +247,13 @@ int trace_xdp_devmap_xmit(struct devmap_xmit_ctx *ctx)
         /* Record bulk events, then userspace can calc average bulk size */
         rec->info += 1;
 
+        /* Record error cases, where no frame were sent */
+        if (ctx->err)
+                rec->err++;
+
+        /* Catch API error of drv ndo_xdp_xmit sent more than count */
+        if (ctx->drops < 0)
+                rec->err++;
+
         return 1;
 }
diff --git a/samples/bpf/xdp_monitor_user.c b/samples/bpf/xdp_monitor_user.c
index 7e18a454924c..dd558cbb2309 100644
--- a/samples/bpf/xdp_monitor_user.c
+++ b/samples/bpf/xdp_monitor_user.c
@@ -117,6 +117,7 @@ struct datarec {
         __u64 processed;
         __u64 dropped;
         __u64 info;
+        __u64 err;
 };
 #define MAX_CPUS 64
 
@@ -152,6 +153,7 @@ static bool map_collect_record(int fd, __u32 key, struct record *rec)
         __u64 sum_processed = 0;
         __u64 sum_dropped = 0;
         __u64 sum_info = 0;
+        __u64 sum_err = 0;
         int i;
 
         if ((bpf_map_lookup_elem(fd, &key, values)) != 0) {
@@ -170,10 +172,13 @@ static bool map_collect_record(int fd, __u32 key, struct record *rec)
                 sum_dropped        += values[i].dropped;
                 rec->cpu[i].info = values[i].info;
                 sum_info        += values[i].info;
+                rec->cpu[i].err = values[i].err;
+                sum_err        += values[i].err;
         }
         rec->total.processed = sum_processed;
         rec->total.dropped   = sum_dropped;
         rec->total.info      = sum_info;
+        rec->total.err       = sum_err;
         return true;
 }
 
@@ -274,6 +279,18 @@ static double calc_info(struct datarec *r, struct datarec *p, double period)
         return pps;
 }
 
+static double calc_err(struct datarec *r, struct datarec *p, double period)
+{
+        __u64 packets = 0;
+        double pps = 0;
+
+        if (period > 0) {
+                packets = r->err - p->err;
+                pps = packets / period;
+        }
+        return pps;
+}
+
 static void stats_print(struct stats_record *stats_rec,
                         struct stats_record *stats_prev,
                         bool err_only)
@@ -412,11 +429,12 @@ static void stats_print(struct stats_record *stats_rec,
 
         /* devmap ndo_xdp_xmit stats */
         {
-                char *fmt1 = "%-15s %-7d %'-12.0f %'-12.0f %'-10.2f %s\n";
-                char *fmt2 = "%-15s %-7s %'-12.0f %'-12.0f %'-10.2f %s\n";
+                char *fmt1 = "%-15s %-7d %'-12.0f %'-12.0f %'-10.2f %s %s\n";
+                char *fmt2 = "%-15s %-7s %'-12.0f %'-12.0f %'-10.2f %s %s\n";
                 struct record *rec, *prev;
-                double drop, info;
+                double drop, info, err;
                 char *i_str = "";
+                char *err_str = "";
 
                 rec  =  &stats_rec->xdp_devmap_xmit;
                 prev = &stats_prev->xdp_devmap_xmit;
@@ -428,22 +446,29 @@ static void stats_print(struct stats_record *stats_rec,
                         pps  = calc_pps(r, p, t);
                         drop = calc_drop(r, p, t);
                         info = calc_info(r, p, t);
+                        err  = calc_err(r, p, t);
                         if (info > 0) {
                                 i_str = "bulk-average";
                                 info = (pps+drop) / info; /* calc avg bulk */
                         }
+                        if (err > 0)
+                                err_str = "drv-err";
                         if (pps > 0 || drop > 0)
                                 printf(fmt1, "devmap-xmit",
-                                       i, pps, drop, info, i_str);
+                                       i, pps, drop, info, i_str, err_str);
                 }
                 pps = calc_pps(&rec->total, &prev->total, t);
                 drop = calc_drop(&rec->total, &prev->total, t);
                 info = calc_info(&rec->total, &prev->total, t);
+                err  = calc_err(&rec->total, &prev->total, t);
                 if (info > 0) {
                         i_str = "bulk-average";
                         info = (pps+drop) / info; /* calc avg bulk */
                 }
-                printf(fmt2, "devmap-xmit", "total", pps, drop, info, i_str);
+                if (err > 0)
+                        err_str = "drv-err";
+                printf(fmt2, "devmap-xmit", "total", pps, drop,
+                       info, i_str, err_str);
         }
 
         printf("\n");