[PATCH v2 1/2] firmware_class: encapsulate firmware loading status

From: Daniel Wagner
Date: Tue Aug 23 2016 - 05:02:29 EST

From: Daniel Wagner <daniel.wagner@xxxxxxxxxxxx>

The firmware user helper code tracks the current state of the loading
process via an member of struct firmware_buf and a completion. Let's
encapsulate this simple state machine into struct fw_status.

We don't need the fw_lock to protect the state machine anymore. First of
all we don't do any RWM operations instead we do either a write or read
to the status variable. Reading the status variable via READ_ONCE
ensures we see the new state whenever we get woken. We are not allowed
to use the complete_all() more than once so we need to filter out all
state transition but the last. That is okay since only the final state
DONE|ABORTED is of interest.

Besides that we also safe a few bytes:

cris etrax-100lx_defconfig

$ bloat-o-meter firmware_class.o.old firmware_class.o.new
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-234 (-234)
function old new delta
_request_firmware 1228 994 -234
Total: Before=2179, After=1945, chg -10.74%

x86_64 FW_LOADER !FW_LOADER_USER_HELPER_FALLBACK

$ bloat-o-meter firmware_class.o.old firmware_class.o.new
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-194 (-194)
function old new delta
_request_firmware 2118 1924 -194
Total: Before=6811, After=6617, chg -2.85%

x86_64 FW_LOADER FW_LOADER_USER_HELPER_FALLBACK

$ bloat-o-meter firmware_class.o.old firmware_class.o.new
add/remove: 0/0 grow/shrink: 2/5 up/down: 4/-193 (-189)
function old new delta
fw_shutdown_notify 81 83 +2
firmware_data_read 162 164 +2
fw_pm_notify 396 394 -2
firmware_loading_store 458 441 -17
firmware_data_write 504 475 -29
firmware_loading_show 92 61 -31
_request_firmware 2931 2817 -114
Total: Before=10328, After=10139, chg -1.83%

Note the variable loading_timeout and the inline function
firmware_loadint_timeout() are used also when no user helper is enabled.
So they need to be moved out side of the ifdef section.

Signed-off-by: Daniel Wagner <daniel.wagner@xxxxxxxxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxxxxx>
Cc: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/base/firmware_class.c | 158 +++++++++++++++++++++++++-----------------
1 file changed, 93 insertions(+), 65 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 22d1760..d3dcf87 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -91,19 +91,88 @@ static inline bool fw_is_builtin_firmware(const struct firmware *fw)
}
#endif

+static int loading_timeout = 60; /* In seconds */
+
+static inline long firmware_loading_timeout(void)
+{
+ return loading_timeout > 0 ? loading_timeout * HZ : MAX_JIFFY_OFFSET;
+}
+
+#ifdef CONFIG_FW_LOADER_USER_HELPER
+
enum {
+ FW_STATUS_UNKNOWN,
FW_STATUS_LOADING,
FW_STATUS_DONE,
- FW_STATUS_ABORT,
+ FW_STATUS_ABORTED,
};

-static int loading_timeout = 60; /* In seconds */
+struct fw_status {
+ unsigned long status;
+ struct completion completion;
+};

-static inline long firmware_loading_timeout(void)
+static void fw_status_init(struct fw_status *fw_st)
{
- return loading_timeout > 0 ? loading_timeout * HZ : MAX_JIFFY_OFFSET;
+ fw_st->status = FW_STATUS_UNKNOWN;
+ init_completion(&fw_st->completion);
+}
+
+static unsigned long __fw_status_get(struct fw_status *fw_st)
+{
+ return READ_ONCE(fw_st->status);
+}
+
+static int fw_status_wait_timeout(struct fw_status *fw_st, long timeout)
+{
+ unsigned long status;
+ int err;
+
+ err = wait_for_completion_interruptible_timeout(&fw_st->completion,
+ timeout);
+ status = READ_ONCE(fw_st->status);
+ if (err == 0 && status == FW_STATUS_ABORTED)
+ return -ENOENT;
+
+ return err;
+}
+
+static void __fw_status_set(struct fw_status *fw_st,
+ unsigned long status)
+{
+ WRITE_ONCE(fw_st->status, status);
+
+ if (status == FW_STATUS_DONE ||
+ status == FW_STATUS_ABORTED)
+ complete_all(&fw_st->completion);
}

+#define fw_status_start(fw_st) \
+ __fw_status_set(fw_st, FW_STATUS_LOADING)
+#define fw_status_done(fw_st) \
+ __fw_status_set(fw_st, FW_STATUS_DONE)
+#define fw_status_aborted(fw_st) \
+ __fw_status_set(fw_st, FW_STATUS_ABORTED)
+#define fw_status_is_loading(fw_st) \
+ (__fw_status_get(fw_st) == FW_STATUS_LOADING)
+#define fw_status_is_done(fw_st) \
+ (__fw_status_get(fw_st) == FW_STATUS_DONE)
+#define fw_status_is_aborted(fw_st) \
+ (__fw_status_get(fw_st) == FW_STATUS_ABORTED)
+
+#else /* CONFIG_FW_LOADER_USER_HELPER */
+
+#define fw_status_wait_timeout(fw_st, long) 0
+
+#define fw_status_start(fw_st)
+#define fw_status_done(fw_st)
+#define fw_status_aborted(fw_st)
+#define fw_status_is_loading(fw_st)
+#define fw_status_is_done(fw_st)
+#define fw_status_is_aborted(fw_st) false
+
+#endif /* !CONFIG_FW_LOADER_USER_HELPER */
+
/* firmware behavior options */
#define FW_OPT_UEVENT (1U << 0)
#define FW_OPT_NOWAIT (1U << 1)
@@ -145,13 +214,12 @@ struct firmware_cache {
struct firmware_buf {
struct kref ref;
struct list_head list;
- struct completion completion;
struct firmware_cache *fwc;
- unsigned long status;
void *data;
size_t size;
size_t allocated_size;
#ifdef CONFIG_FW_LOADER_USER_HELPER
+ struct fw_status fw_st;
bool is_paged_buf;
bool need_uevent;
struct page **pages;
@@ -205,8 +273,8 @@ static struct firmware_buf *__allocate_fw_buf(const char *fw_name,
buf->fwc = fwc;
buf->data = dbuf;
buf->allocated_size = size;
- init_completion(&buf->completion);
#ifdef CONFIG_FW_LOADER_USER_HELPER
+ fw_status_init(&buf->fw_st);
INIT_LIST_HEAD(&buf->pending_list);
#endif

@@ -305,15 +373,6 @@ static const char * const fw_path[] = {
module_param_string(path, fw_path_para, sizeof(fw_path_para), 0644);
MODULE_PARM_DESC(path, "customized firmware image search path with a higher priority than default path");

-static void fw_finish_direct_load(struct device *device,
- struct firmware_buf *buf)
-{
- mutex_lock(&fw_lock);
- set_bit(FW_STATUS_DONE, &buf->status);
- complete_all(&buf->completion);
- mutex_unlock(&fw_lock);
-}
-
static int
fw_get_filesystem_firmware(struct device *device, struct firmware_buf *buf)
{
@@ -360,7 +419,7 @@ fw_get_filesystem_firmware(struct device *device, struct firmware_buf *buf)
}
dev_dbg(device, "direct-loading %s\n", buf->fw_id);
buf->size = size;
- fw_finish_direct_load(device, buf);
+ fw_status_done(&buf->fw_st);
break;
}
__putname(path);
@@ -478,12 +537,11 @@ static void __fw_load_abort(struct firmware_buf *buf)
* There is a small window in which user can write to 'loading'
* between loading done and disappearance of 'loading'
*/
- if (test_bit(FW_STATUS_DONE, &buf->status))
+ if (fw_status_is_done(&buf->fw_st))
return;

list_del_init(&buf->pending_list);
- set_bit(FW_STATUS_ABORT, &buf->status);
- complete_all(&buf->completion);
+ fw_status_aborted(&buf->fw_st);
}

static void fw_load_abort(struct firmware_priv *fw_priv)
@@ -496,9 +554,6 @@ static void fw_load_abort(struct firmware_priv *fw_priv)
fw_priv->buf = NULL;
}

-#define is_fw_load_aborted(buf) \
- test_bit(FW_STATUS_ABORT, &(buf)->status)
-
static LIST_HEAD(pending_fw_head);

/* reboot notifier for avoid deadlock with usermode_lock */
@@ -596,10 +651,8 @@ static ssize_t firmware_loading_show(struct device *dev,
struct firmware_priv *fw_priv = to_firmware_priv(dev);
int loading = 0;

- mutex_lock(&fw_lock);
if (fw_priv->buf)
- loading = test_bit(FW_STATUS_LOADING, &fw_priv->buf->status);
- mutex_unlock(&fw_lock);
+ loading = fw_status_is_loading(&fw_priv->buf->fw_st);

return sprintf(buf, "%d\n", loading);
}
@@ -653,23 +706,20 @@ static ssize_t firmware_loading_store(struct device *dev,
switch (loading) {
case 1:
/* discarding any previous partial load */
- if (!test_bit(FW_STATUS_DONE, &fw_buf->status)) {
+ if (!fw_status_is_done(&fw_buf->fw_st)) {
for (i = 0; i < fw_buf->nr_pages; i++)
__free_page(fw_buf->pages[i]);
vfree(fw_buf->pages);
fw_buf->pages = NULL;
fw_buf->page_array_size = 0;
fw_buf->nr_pages = 0;
- set_bit(FW_STATUS_LOADING, &fw_buf->status);
+ fw_status_start(&fw_buf->fw_st);
}
break;
case 0:
- if (test_bit(FW_STATUS_LOADING, &fw_buf->status)) {
+ if (fw_status_is_loading(&fw_buf->fw_st)) {
int rc;

- set_bit(FW_STATUS_DONE, &fw_buf->status);
- clear_bit(FW_STATUS_LOADING, &fw_buf->status);
-
/*
* Several loading requests may be pending on
* one same firmware buf, so let all requests
@@ -691,10 +741,11 @@ static ssize_t firmware_loading_store(struct device *dev,
*/
list_del_init(&fw_buf->pending_list);
if (rc) {
- set_bit(FW_STATUS_ABORT, &fw_buf->status);
+ fw_status_aborted(&fw_buf->fw_st);
written = rc;
+ } else {
+ fw_status_done(&fw_buf->fw_st);
}
- complete_all(&fw_buf->completion);
break;
}
/* fallthrough */
@@ -702,7 +753,7 @@ static ssize_t firmware_loading_store(struct device *dev,
dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading);
/* fallthrough */
case -1:
- fw_load_abort(fw_priv);
+ fw_status_aborted(&fw_buf->fw_st);
break;
}
out:
@@ -755,7 +806,7 @@ static ssize_t firmware_data_read(struct file *filp, struct kobject *kobj,

mutex_lock(&fw_lock);
buf = fw_priv->buf;
- if (!buf || test_bit(FW_STATUS_DONE, &buf->status)) {
+ if (!buf || fw_status_is_done(&buf->fw_st)) {
ret_count = -ENODEV;
goto out;
}
@@ -842,7 +893,7 @@ static ssize_t firmware_data_write(struct file *filp, struct kobject *kobj,

mutex_lock(&fw_lock);
buf = fw_priv->buf;
- if (!buf || test_bit(FW_STATUS_DONE, &buf->status)) {
+ if (!buf || fw_status_is_done(&buf->fw_st)) {
retval = -ENODEV;
goto out;
}
@@ -955,8 +1006,7 @@ static int _request_firmware_load(struct firmware_priv *fw_priv,
timeout = MAX_JIFFY_OFFSET;
}

- retval = wait_for_completion_interruptible_timeout(&buf->completion,
- timeout);
+ retval = fw_status_wait_timeout(&buf->fw_st, timeout);
if (retval == -ERESTARTSYS || !retval) {
mutex_lock(&fw_lock);
fw_load_abort(fw_priv);
@@ -965,7 +1015,7 @@ static int _request_firmware_load(struct firmware_priv *fw_priv,
retval = 0;
}

- if (is_fw_load_aborted(buf))
+ if (fw_status_is_aborted(&buf->fw_st))
retval = -EAGAIN;
else if (buf->is_paged_buf && !buf->data)
retval = -ENOMEM;
@@ -1015,35 +1065,12 @@ fw_load_from_user_helper(struct firmware *firmware, const char *name,
return -ENOENT;
}

-/* No abort during direct loading */
-#define is_fw_load_aborted(buf) false
-
#ifdef CONFIG_PM_SLEEP
static inline void kill_requests_without_uevent(void) { }
#endif

#endif /* CONFIG_FW_LOADER_USER_HELPER */

-
-/* wait until the shared firmware_buf becomes ready (or error) */
-static int sync_cached_firmware_buf(struct firmware_buf *buf)
-{
- int ret = 0;
-
- mutex_lock(&fw_lock);
- while (!test_bit(FW_STATUS_DONE, &buf->status)) {
- if (is_fw_load_aborted(buf)) {
- ret = -ENOENT;
- break;
- }
- mutex_unlock(&fw_lock);
- ret = wait_for_completion_interruptible(&buf->completion);
- mutex_lock(&fw_lock);
- }
- mutex_unlock(&fw_lock);
- return ret;
-}
-
/* prepare firmware and firmware_buf structs;
* return 0 if a firmware is already assigned, 1 if need to load one,
* or a negative error code
@@ -1077,7 +1104,8 @@ _request_firmware_prepare(struct firmware **firmware_p, const char *name,
firmware->priv = buf;

if (ret > 0) {
- ret = sync_cached_firmware_buf(buf);
+ ret = fw_status_wait_timeout(&buf->fw_st,
+ firmware_loading_timeout());
if (!ret) {
fw_set_page_data(buf, firmware);
return 0; /* assigned */
@@ -1095,7 +1123,7 @@ static int assign_firmware_buf(struct firmware *fw, struct device *device,
struct firmware_buf *buf = fw->priv;

mutex_lock(&fw_lock);
- if (!buf->size || is_fw_load_aborted(buf)) {
+ if (!buf->size || fw_status_is_aborted(&buf->fw_st)) {
mutex_unlock(&fw_lock);
return -ENOENT;
}
--
2.7.4