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Date: Mon, 14 Jun 2021 08:50:35 -0700
From: Kees Cook <keescook@...omium.org>
To: Jarmo Tiitto <jarmo.tiitto@...il.com>
Cc: Sami Tolvanen <samitolvanen@...gle.com>,
Bill Wendling <wcw@...gle.com>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
clang-built-linux@...glegroups.com, linux-kernel@...r.kernel.org,
morbo@...gle.com
Subject: Re: [RFC PATCH 5/5] pgo: Cleanup code in pgo/fs.c
On Sat, Jun 12, 2021 at 06:24:26AM +0300, Jarmo Tiitto wrote:
> Cleanups to comments and punctuation.
> Cleanup return path in pgo_module_init.
Can you include these changes in the patches that introduce the various
comments, etc? It looks like most (all?) are from patches in this
series.
-Kees
>
> Signed-off-by: Jarmo Tiitto <jarmo.tiitto@...il.com>
> ---
> kernel/pgo/fs.c | 47 +++++++++++++++++++++++------------------------
> 1 file changed, 23 insertions(+), 24 deletions(-)
>
> diff --git a/kernel/pgo/fs.c b/kernel/pgo/fs.c
> index 98b982245b58..855d5e3050fa 100644
> --- a/kernel/pgo/fs.c
> +++ b/kernel/pgo/fs.c
> @@ -294,7 +294,7 @@ static int prf_open(struct inode *inode, struct file *file)
> int err = -EINVAL;
>
> if (WARN_ON(!inode->i_private)) {
> - /* bug: inode was not initialized by us */
> + /* Bug: inode was not initialized by us. */
> return err;
> }
>
> @@ -302,7 +302,7 @@ static int prf_open(struct inode *inode, struct file *file)
> if (!data)
> return -ENOMEM;
>
> - /* Get prf_object of this inode */
> + /* Get prf_object of this inode. */
> data->core = inode->i_private;
>
> /* Get initial buffer size. */
> @@ -425,17 +425,17 @@ static void pgo_module_init(struct module *mod)
> char fname[MODULE_NAME_LEN + 9]; /* +strlen(".profraw") */
> unsigned long flags;
>
> - /* add new prf_object entry for the module */
> + /* Add new prf_object entry for the module. */
> po = kzalloc(sizeof(*po), GFP_KERNEL);
> if (!po)
> - goto out;
> + return; /* -ENOMEM */
>
> po->mod_name = mod->name;
>
> fname[0] = 0;
> snprintf(fname, sizeof(fname), "%s.profraw", po->mod_name);
>
> - /* setup prf_object sections */
> + /* Setup prf_object sections. */
> po->data = mod->prf_data;
> po->data_num = prf_get_count(mod->prf_data,
> (char *)mod->prf_data + mod->prf_data_size, sizeof(po->data[0]));
> @@ -452,20 +452,19 @@ static void pgo_module_init(struct module *mod)
> po->vnds_num = prf_get_count(mod->prf_vnds,
> (char *)mod->prf_vnds + mod->prf_vnds_size, sizeof(po->vnds[0]));
>
> - /* create debugfs entry */
> + /* Create debugfs entry. */
> po->file = debugfs_create_file(fname, 0600, directory, po, &prf_fops);
> if (!po->file) {
> pr_err("Failed to setup module pgo: %s", fname);
> kfree(po);
> - goto out;
> - }
>
> - /* finally enable profiling for the module */
> - flags = prf_list_lock();
> - list_add_tail_rcu(&po->link, &prf_list);
> - prf_list_unlock(flags);
> + } else {
> + /* Finally enable profiling for the module. */
> + flags = prf_list_lock();
> + list_add_tail_rcu(&po->link, &prf_list);
> + prf_list_unlock(flags);
> + }
>
> -out:
> return;
> }
>
> @@ -477,33 +476,33 @@ static int pgo_module_notifier(struct notifier_block *nb, unsigned long event,
> unsigned long flags;
>
> if (event == MODULE_STATE_LIVE) {
> - /* does the module have profiling info? */
> + /* Does the module have profiling info? */
> if (mod->prf_data
> && mod->prf_cnts
> && mod->prf_names
> && mod->prf_vnds) {
>
> - /* setup module profiling */
> + /* Setup module profiling. */
> pgo_module_init(mod);
> }
> }
>
> if (event == MODULE_STATE_GOING) {
> - /* find the prf_object from the list */
> + /* Find the prf_object from the list. */
> rcu_read_lock();
>
> list_for_each_entry_rcu(po, &prf_list, link) {
> if (strcmp(po->mod_name, mod->name) == 0)
> goto out_unlock;
> }
> - /* no such module */
> + /* No such module. */
> po = NULL;
>
> out_unlock:
> rcu_read_unlock();
>
> if (po) {
> - /* remove from profiled modules */
> + /* Remove from profiled modules. */
> flags = prf_list_lock();
> list_del_rcu(&po->link);
> prf_list_unlock(flags);
> @@ -511,7 +510,7 @@ static int pgo_module_notifier(struct notifier_block *nb, unsigned long event,
> debugfs_remove(po->file);
> po->file = NULL;
>
> - /* cleanup memory */
> + /* Cleanup memory. */
> kfree_rcu(po, rcu);
> }
> }
> @@ -528,7 +527,7 @@ static int __init pgo_init(void)
> {
> unsigned long flags;
>
> - /* Init profiler vmlinux core entry */
> + /* Init profiler vmlinux core entry. */
> memset(&prf_vmlinux, 0, sizeof(prf_vmlinux));
> prf_vmlinux.data = __llvm_prf_data_start;
> prf_vmlinux.data_num = prf_get_count(__llvm_prf_data_start,
> @@ -546,7 +545,7 @@ static int __init pgo_init(void)
> prf_vmlinux.vnds_num = prf_get_count(__llvm_prf_vnds_start,
> __llvm_prf_vnds_end, sizeof(__llvm_prf_vnds_start[0]));
>
> - /* enable profiling */
> + /* Enable profiling. */
> flags = prf_list_lock();
> prf_vmlinux.mod_name = "vmlinux";
> list_add_tail_rcu(&prf_vmlinux.link, &prf_list);
> @@ -565,10 +564,10 @@ static int __init pgo_init(void)
> &prf_reset_fops))
> goto err_remove;
>
> - /* register module notifer */
> + /* Register module notifer. */
> register_module_notifier(&pgo_module_nb);
>
> - /* show notice why the system slower: */
> + /* Show notice why the system slower: */
> pr_notice("Clang PGO instrumentation is active.");
>
> return 0;
> @@ -581,7 +580,7 @@ static int __init pgo_init(void)
> /* Remove debugfs entries. */
> static void __exit pgo_exit(void)
> {
> - /* unsubscribe the notifier and do cleanup. */
> + /* Unsubscribe the notifier and do cleanup. */
> unregister_module_notifier(&pgo_module_nb);
>
> debugfs_remove_recursive(directory);
> --
> 2.32.0
>
--
Kees Cook
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