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Tue, 12 Aug 2025 09:21:09 -0700 (PDT) Received: from localhost.localdomain ([2406:5900:2:f21::2a1]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-76bccfdf9bdsm29794035b3a.111.2025.08.12.09.21.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Aug 2025 09:21:08 -0700 (PDT) From: Ryan Chung To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyer@efficios.com Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kernel-mentees@lists.linux.dev, Ryan Chung Subject: [PATCH] trace/trace_fprobe.c: TODO: handle filter, nofilter or symbol list Date: Wed, 13 Aug 2025 01:21:01 +0900 Message-ID: <20250812162101.5981-1-seokwoo.chung130@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Resolve TODO in `__register_trace_fprobe()`: parse `tf->symbol` robustly (support `sym!filter` and comma-separated lists), trim tokens, ignore empties, deduplicate symbols, use bulk registration for lists, return `-EEXIST` if already registered, and preserve lockdown/tracepoint deferral semantics. Please note that this was my personal interpretation of what TODO required here. Welcoming any feedback. Signed-off-by: Ryan Chung --- kernel/trace/trace_fprobe.c | 102 +++++++++++++++++++++++++++++++++++- 1 file changed, 100 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c index b40fa59159ac..37d4260b9012 100644 --- a/kernel/trace/trace_fprobe.c +++ b/kernel/trace/trace_fprobe.c @@ -12,6 +12,8 @@ #include #include #include +#include +#include #include "trace_dynevent.h" #include "trace_probe.h" @@ -762,8 +764,104 @@ static int __register_trace_fprobe(struct trace_fprobe *tf) return __regsiter_tracepoint_fprobe(tf); } - /* TODO: handle filter, nofilter or symbol list */ - return register_fprobe(&tf->fp, tf->symbol, NULL); + /* Parse tf->symbol */ + { + char *spec, *bang, *p; + int n = 0, w = 0, j, rc; + char **syms = NULL; + + spec = kstrdup(tf->symbol, GFP_KERNEL); + if (!spec) + return -ENOMEM; + + /* If a '!' exists, treat it as single symbol + filter */ + bang = strchr(spec, '!'); + if (bang) { + char *sym, *flt; + + *bang = '\0'; + sym = strim(spec); + flt = strim(bang + 1); + + if (!*sym || !*flt) { + kfree(spec); + return -EINVAL; /* reject empty symbol/filter */ + } + + rc = register_fprobe(&tf->fp, sym, flt); + kfree(spec); + return rc; + } + + /* Comma list (or single symbol without '!') */ + /* First pass: count non-empty tokens */ + p = spec; + while (p) { + char *tok = strsep(&p, ","); + if (tok && *strim(tok)) + n++; + } + + if (n == 0){ + kfree(spec); + return -EINVAL; + } + + /* Allocate array for pointers into spec (callee copies/consumes) */ + syms = kcalloc(n, sizeof(*syms), GFP_KERNEL); + if (!syms) { + kfree(spec); + return -ENOMEM; + } + + /* Second pass: fill, skipping empties */ + p = spec; + while (p) { + char *tok = strsep(&p, ","); + char *s; + + if (!tok) + break; + s = strim(tok); + if (!*s) + continue; + syms[w++] = s; + } + + /* Dedup in-place */ + for (i = 0; i < w; i++){ + if (!syms[i]) + continue; + for (j = i + 1; j < w; j++) { + if (syms[j] && !strcmp(syms[i], syms[j])) + syms[j] = NULL; + } + } + + /* Compact */ + for (i = 0, j = 0; i < w; i++) { + if (syms[i]) + syms[j++] = syms[i]; + } + w = j; + + /* After dedup, ensure we still have at least one symbol */ + if (w == 0){ + kfree(syms); + kfree(spec); + return -EINVAL; + } + + /* Register list or single symbol, using the existing bulk API */ + if (w == 1) + rc = register_fprobe(&tf->fp, syms[0], NULL); + else + rc = register_fprobe_syms(&tf->fp, (const char **)syms, w); + + kfree(syms); + kfree(spec); + return rc; + } } /* Internal unregister function - just handle fprobe and flags */ -- 2.43.0