[v3,07/20] firmware: move loading timeout under struct firmware_fallback_config
diff mbox

Message ID 20180310141501.2214-8-mcgrof@kernel.org
State New
Headers show

Commit Message

Luis Chamberlain March 10, 2018, 2:14 p.m. UTC
The timeout is a fallback construct, so we can just stuff the
timeout configuration under struct firmware_fallback_config.

While at it, add a few helpers which vets the use of getting or
setting the timeout as an int. The main use of the timeout is
to set a timeout for completion, and that is used as an unsigned
long. There a few cases however where it makes sense to get or
set the timeout as an int, the helpers annotate these use cases
have been properly vetted for.

Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
---
 drivers/base/firmware_loader.c | 46 ++++++++++++++++++++++++++++++------------
 1 file changed, 33 insertions(+), 13 deletions(-)

Comments

gregkh March 14, 2018, 6:56 p.m. UTC | #1
On Sat, Mar 10, 2018 at 06:14:48AM -0800, Luis R. Rodriguez wrote:
> The timeout is a fallback construct, so we can just stuff the
> timeout configuration under struct firmware_fallback_config.

Why?  What does it matter?

> While at it, add a few helpers which vets the use of getting or
> setting the timeout as an int. The main use of the timeout is
> to set a timeout for completion, and that is used as an unsigned
> long. There a few cases however where it makes sense to get or
> set the timeout as an int, the helpers annotate these use cases
> have been properly vetted for.

This feels really odd to me.  Why would you want to use it as an int,
just keep it the same "size" everywhere and it should be simpler and
easier to keep working correctly over time.

thanks,

greg k-h
Luis Chamberlain March 14, 2018, 10:33 p.m. UTC | #2
On Wed, Mar 14, 2018 at 11:56 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> On Sat, Mar 10, 2018 at 06:14:48AM -0800, Luis R. Rodriguez wrote:
>> The timeout is a fallback construct, so we can just stuff the
>> timeout configuration under struct firmware_fallback_config.
>
> Why?  What does it matter?

Because we want to remove direct access to things which the direct
firmware loader should not care about, and instead have proper
wrappers so that the fallback code implements it when needed. Part of
the motivation for this then was to move all fallback code into its
own file therefore compartmentalizing it.

>> While at it, add a few helpers which vets the use of getting or
>> setting the timeout as an int. The main use of the timeout is
>> to set a timeout for completion, and that is used as an unsigned
>> long. There a few cases however where it makes sense to get or
>> set the timeout as an int, the helpers annotate these use cases
>> have been properly vetted for.
>
> This feels really odd to me.  Why would you want to use it as an int,
> just keep it the same "size" everywhere and it should be simpler and
> easier to keep working correctly over time.

One is the input/output we provide for it uses ints all over so its
much easier to handle this as an int consistently in most places and
only deal with the long where needed. See above uses of
simple_strtol(), add_uevent_var(). Otherwise the inverse has to be
done. This was easier to deal with and vet for.

 Luis

Patch
diff mbox

diff --git a/drivers/base/firmware_loader.c b/drivers/base/firmware_loader.c
index 2d819875348d..9757f9fff01e 100644
--- a/drivers/base/firmware_loader.c
+++ b/drivers/base/firmware_loader.c
@@ -266,21 +266,38 @@  static inline bool fw_state_is_aborted(struct fw_priv *fw_priv)
  *
  * @force_sysfs_fallback: force the sysfs fallback mechanism to be used
  * 	as if one had enabled CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y.
+ * @old_timeout: for internal use
+ * @loading_timeout: the timeout to wait for the fallback mechanism before
+ * 	giving up, in seconds.
  */
 struct firmware_fallback_config {
-	bool force_sysfs_fallback;
+	const bool force_sysfs_fallback;
+	int old_timeout;
+	int loading_timeout;
 };
 
-static const struct firmware_fallback_config fw_fallback_config = {
+static struct firmware_fallback_config fw_fallback_config = {
 	.force_sysfs_fallback = IS_ENABLED(CONFIG_FW_LOADER_USER_HELPER_FALLBACK),
+	.loading_timeout = 60,
+	.old_timeout = 60,
 };
 
-static int old_timeout;
-static int loading_timeout = 60;	/* In seconds */
+/* These getters are vetted to use int properly */
+static inline int __firmware_loading_timeout(void)
+{
+	return fw_fallback_config.loading_timeout;
+}
+
+/* These setters are vetted to use int properly */
+static void __fw_fallback_set_timeout(int timeout)
+{
+	fw_fallback_config.loading_timeout = timeout;
+}
 
 static inline long firmware_loading_timeout(void)
 {
-	return loading_timeout > 0 ? loading_timeout * HZ : MAX_JIFFY_OFFSET;
+	return __firmware_loading_timeout() > 0 ?
+		__firmware_loading_timeout() * HZ : MAX_JIFFY_OFFSET;
 }
 
 /*
@@ -291,14 +308,14 @@  static inline long firmware_loading_timeout(void)
  */
 static void fw_fallback_set_cache_timeout(void)
 {
-	old_timeout = loading_timeout;
-	loading_timeout = 10;
+	fw_fallback_config.old_timeout = __firmware_loading_timeout();
+	__fw_fallback_set_timeout(10);
 }
 
 /* Restores the timeout to the value last configured during normal operation */
 static void fw_fallback_set_default_timeout(void)
 {
-	loading_timeout =  old_timeout;
+	__fw_fallback_set_timeout(fw_fallback_config.old_timeout);
 }
 
 static inline bool fw_sysfs_done(struct fw_priv *fw_priv)
@@ -677,7 +694,7 @@  static void kill_pending_fw_fallback_reqs(bool only_kill_custom)
 static ssize_t timeout_show(struct class *class, struct class_attribute *attr,
 			    char *buf)
 {
-	return sprintf(buf, "%d\n", loading_timeout);
+	return sprintf(buf, "%d\n", __firmware_loading_timeout());
 }
 
 /**
@@ -696,9 +713,12 @@  static ssize_t timeout_show(struct class *class, struct class_attribute *attr,
 static ssize_t timeout_store(struct class *class, struct class_attribute *attr,
 			     const char *buf, size_t count)
 {
-	loading_timeout = simple_strtol(buf, NULL, 10);
-	if (loading_timeout < 0)
-		loading_timeout = 0;
+	int tmp_loading_timeout = simple_strtol(buf, NULL, 10);
+
+	if (tmp_loading_timeout < 0)
+		tmp_loading_timeout = 0;
+
+	__fw_fallback_set_timeout(tmp_loading_timeout);
 
 	return count;
 }
@@ -721,7 +741,7 @@  static int do_firmware_uevent(struct fw_sysfs *fw_sysfs, struct kobj_uevent_env
 {
 	if (add_uevent_var(env, "FIRMWARE=%s", fw_sysfs->fw_priv->fw_name))
 		return -ENOMEM;
-	if (add_uevent_var(env, "TIMEOUT=%i", loading_timeout))
+	if (add_uevent_var(env, "TIMEOUT=%i", __firmware_loading_timeout()))
 		return -ENOMEM;
 	if (add_uevent_var(env, "ASYNC=%d", fw_sysfs->nowait))
 		return -ENOMEM;