[v3,4/8] ebpf: improve error trace events

Commit Message

Daniel P. Berrangé Oct. 23, 2024, 8:50 a.m. UTC

A design pattern of

   trace_foo_error("descriptive string")

is undesirable because it does not allow for filtering trace events
based on the error scenario. Split eBPF error trace event into three
separate events to address this filtering need.

Signed-off-by: Daniel P. Berrangé <[e-mail]>
---
 ebpf/ebpf_rss.c   | 10 +++++-----
 ebpf/trace-events |  4 +++-
 2 files changed, 8 insertions(+), 6 deletions(-)

Patch

diff --git a/ebpf/ebpf_rss.c b/ebpf/ebpf_rss.c
index 0c42355a93..d39916b368 100644
--- a/ebpf/ebpf_rss.c
+++ b/ebpf/ebpf_rss.c
@@ -53,21 +53,21 @@  static bool ebpf_rss_mmap(struct EBPFRSSContext *ctx)
                                    PROT_READ | PROT_WRITE, MAP_SHARED,
                                    ctx->map_configuration, 0);
     if (ctx->mmap_configuration == MAP_FAILED) {
-        trace_ebpf_error("eBPF RSS", "can not mmap eBPF configuration array");
+        trace_ebpf_rss_mmap_error(ctx, "configuration");
         return false;
     }
     ctx->mmap_toeplitz_key = mmap(NULL, qemu_real_host_page_size(),
                                    PROT_READ | PROT_WRITE, MAP_SHARED,
                                    ctx->map_toeplitz_key, 0);
     if (ctx->mmap_toeplitz_key == MAP_FAILED) {
-        trace_ebpf_error("eBPF RSS", "can not mmap eBPF toeplitz key");
+        trace_ebpf_rss_mmap_error(ctx, "toeplitz key");
         goto toeplitz_fail;
     }
     ctx->mmap_indirections_table = mmap(NULL, qemu_real_host_page_size(),
                                    PROT_READ | PROT_WRITE, MAP_SHARED,
                                    ctx->map_indirections_table, 0);
     if (ctx->mmap_indirections_table == MAP_FAILED) {
-        trace_ebpf_error("eBPF RSS", "can not mmap eBPF indirection table");
+        trace_ebpf_rss_mmap_error(ctx, "indirections table");
         goto indirection_fail;
     }
 
@@ -105,14 +105,14 @@  bool ebpf_rss_load(struct EBPFRSSContext *ctx)
 
     rss_bpf_ctx = rss_bpf__open();
     if (rss_bpf_ctx == NULL) {
-        trace_ebpf_error("eBPF RSS", "can not open eBPF RSS object");
+        trace_ebpf_rss_open_error(ctx);
         goto error;
     }
 
     bpf_program__set_type(rss_bpf_ctx->progs.tun_rss_steering_prog, BPF_PROG_TYPE_SOCKET_FILTER);
 
     if (rss_bpf__load(rss_bpf_ctx)) {
-        trace_ebpf_error("eBPF RSS", "can not load RSS program");
+        trace_ebpf_rss_load_error(ctx);
         goto error;
     }
 
diff --git a/ebpf/trace-events b/ebpf/trace-events
index b3ad1a35f2..a0f157be37 100644
--- a/ebpf/trace-events
+++ b/ebpf/trace-events
@@ -1,4 +1,6 @@ 
 # See docs/devel/tracing.rst for syntax documentation.
 
 # ebpf-rss.c
-ebpf_error(const char *s1, const char *s2) "error in %s: %s"
+ebpf_rss_load_error(void *ctx) "ctx=%p"
+ebpf_rss_mmap_error(void *ctx, const char *object) "ctx=%p object=%s"
+ebpf_rss_open_error(void *ctx) "ctx=%p"