firmware: fix checking for return values for fw_add_devm_name()

BugLink: http://bugs.launchpad.net/bugs/1786352
[ Upstream commit d15d7311550983be97dca44ad68cbc2ca001297b ]

Currently fw_add_devm_name() returns 1 if the firmware cache
was already set. This makes it complicated for us to check for
correctness. It is actually non-fatal if the firmware cache
is already setup, so just return 0, and simplify the checkers.

fw_add_devm_name() adds device's name onto the devres for the
device so that prior to suspend we cache the firmware onto memory,
so that on resume the firmware is reliably available. We never
were checking for success for this call though, meaning in some
really rare cases we my have never setup the firmware cache for
a device, which could in turn make resume fail.

This is all theoretical, no known issues have been reported.
This small issue has been present way since the addition of the
devres firmware cache names on v3.7.

Fixes: f531f05ae9437 ("firmware loader: store firmware name into devres list")
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 4b57cf5bc81d15f47069832a5a631a9f254e567a..0e742681441659d5b6a14de83f6be3f9f013e121 100644 (file)
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -499,7 +499,7 @@ static int fw_add_devm_name(struct device *dev, const char *name)
 
        fwn = fw_find_devm_name(dev, name);
        if (fwn)
-               return 1;
+               return 0;
 
        fwn = devres_alloc(fw_name_devm_release, sizeof(struct fw_name_devm),
                           GFP_KERNEL);
@@ -527,6 +527,7 @@ static int assign_firmware_buf(struct firmware *fw, struct device *device,
                               unsigned int opt_flags)
 {
        struct firmware_buf *buf = fw->priv;
+       int ret;
 
        mutex_lock(&fw_lock);
        if (!buf->size || fw_state_is_aborted(&buf->fw_st)) {
@@ -543,8 +544,13 @@ static int assign_firmware_buf(struct firmware *fw, struct device *device,
         */
        /* don't cache firmware handled without uevent */
        if (device && (opt_flags & FW_OPT_UEVENT) &&
-           !(opt_flags & FW_OPT_NOCACHE))
-               fw_add_devm_name(device, buf->fw_id);
+           !(opt_flags & FW_OPT_NOCACHE)) {
+               ret = fw_add_devm_name(device, buf->fw_id);
+               if (ret) {
+                       mutex_unlock(&fw_lock);
+                       return ret;
+               }
+       }
 
        /*
         * After caching firmware image is started, let it piggyback