linux-kernel - [PATCH v2 2/3] libkmod/libkmod-module: add refcnt fd helper

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Message-Id: <20210810051602.3067384-3-mcgrof@kernel.org>
Date:   Mon,  9 Aug 2021 22:16:01 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     lucas.demarchi@...el.com, linux-modules@...r.kernel.org
Cc:     live-patching@...r.kernel.org, fstests@...r.kernel.org,
        linux-block@...r.kernel.org, hare@...e.de, dgilbert@...erlog.com,
        jeyu@...nel.org, osandov@...com, linux-kernel@...r.kernel.org,
        Luis Chamberlain <mcgrof@...nel.org>
Subject: [PATCH v2 2/3] libkmod/libkmod-module: add refcnt fd helper

The first part of kmod_module_get_refcnt() is to open the
file descriptor for the refcnt file. Add a helper to do this
as it can then be used in other cases in the library.

Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
---
 libkmod/libkmod-module.c | 37 ++++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/libkmod/libkmod-module.c b/libkmod/libkmod-module.c
index 6e0ff1a..04bb4d9 100644
--- a/libkmod/libkmod-module.c
+++ b/libkmod/libkmod-module.c
@@ -1877,25 +1877,16 @@ done:
 	return size;
 }
 
-/**
- * kmod_module_get_refcnt:
- * @mod: kmod module
- *
- * Get the ref count of this @mod, as returned by Linux Kernel, by reading
- * /sys filesystem.
- *
- * Returns: the reference count on success or < 0 on failure.
- */
-KMOD_EXPORT int kmod_module_get_refcnt(const struct kmod_module *mod)
+static int kmod_module_get_refcnt_fd(const struct kmod_module *mod)
 {
 	char path[PATH_MAX];
-	long refcnt;
 	int fd, err;
 
 	if (mod == NULL)
 		return -ENOENT;
 
 	snprintf(path, sizeof(path), "/sys/module/%s/refcnt", mod->name);
+
 	fd = open(path, O_RDONLY|O_CLOEXEC);
 	if (fd < 0) {
 		err = -errno;
@@ -1903,12 +1894,32 @@ KMOD_EXPORT int kmod_module_get_refcnt(const struct kmod_module *mod)
 			path, strerror(errno));
 		return err;
 	}
+	return fd;
+}
+
+/**
+ * kmod_module_get_refcnt:
+ * @mod: kmod module
+ *
+ * Get the ref count of this @mod, as returned by Linux Kernel, by reading
+ * /sys filesystem.
+ *
+ * Returns: the reference count on success or < 0 on failure.
+ */
+KMOD_EXPORT int kmod_module_get_refcnt(const struct kmod_module *mod)
+{
+	long refcnt;
+	int fd, err;
+
+	fd = kmod_module_get_refcnt_fd(mod);
+	if (fd < 0)
+		return fd;
 
 	err = read_str_long(fd, &refcnt, 10);
 	close(fd);
 	if (err < 0) {
-		ERR(mod->ctx, "could not read integer from '%s': '%s'\n",
-			path, strerror(-err));
+		ERR(mod->ctx, "could not read integer from '/sys/module/%s/refcnt': '%s'\n",
+		    mod->name, strerror(-err));
 		return err;
 	}
 
-- 
2.30.2