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Subject[PATCH v5 1/2] firmware_loader: use -ETIMEDOUT instead of -EAGAIN in fw_load_sysfs_fallback
Date
The only motivation for using -EAGAIN in commit 0542ad88fbdd81bb
("firmware loader: Fix _request_firmware_load() return val for fw load
abort") was to distinguish the error from -ENOMEM, and so there is no
real reason in keeping it. Keeping -ETIMEDOU is much telling of what the
reason for a failure is, so just use that.

The rest is just trying to document a bit more of the motivations for the
error codes, as otherwise we'd lose this information easily.

Suggested-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
---
drivers/base/firmware_loader/fallback.c | 36 ++++++++++++++++++-------
1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
index 91899d185e31..bc25bb5d1ed6 100644
--- a/drivers/base/firmware_loader/fallback.c
+++ b/drivers/base/firmware_loader/fallback.c
@@ -70,7 +70,31 @@ static inline bool fw_sysfs_loading(struct fw_priv *fw_priv)

static inline int fw_sysfs_wait_timeout(struct fw_priv *fw_priv, long timeout)
{
- return __fw_state_wait_common(fw_priv, timeout);
+ int ret = __fw_state_wait_common(fw_priv, timeout);
+
+ /*
+ * A signal could be sent to abort a wait. Consider Android's init
+ * gettting a SIGCHLD, which in turn was the same process issuing the
+ * sysfs store call for the fallback. In such cases we want to be able
+ * to tell apart in userspace when a signal caused a failure on the
+ * wait. In such cases we'd get -ERESTARTSYS.
+ *
+ * Likewise though another race can happen and abort the load earlier.
+ *
+ * In either case the situation is interrupted so we just inform
+ * userspace of that and we end things right away.
+ *
+ * When we really time out just tell userspace it should try again,
+ * perhaps later.
+ */
+ if (ret == -ERESTARTSYS || fw_state_is_aborted(fw_priv))
+ ret = -EINTR;
+ else if (ret == -ETIMEDOUT)
+ ret = -EAGAIN;
+ else if (fw_priv->is_paged_buf && !fw_priv->data)
+ ret = -ENOMEM;
+
+ return ret;
}

struct fw_sysfs {
@@ -526,20 +550,12 @@ static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs, long timeout)
}

retval = fw_sysfs_wait_timeout(fw_priv, timeout);
- if (retval < 0 && retval != -ENOENT) {
+ if (retval < 0) {
mutex_lock(&fw_lock);
fw_load_abort(fw_sysfs);
mutex_unlock(&fw_lock);
}

- if (fw_state_is_aborted(fw_priv)) {
- if (retval == -ERESTARTSYS)
- retval = -EINTR;
- else
- retval = -EAGAIN;
- } else if (fw_priv->is_paged_buf && !fw_priv->data)
- retval = -ENOMEM;
-
device_del(f_dev);
err_put_dev:
put_device(f_dev);
--
2.26.2
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