devcoredump: Send uevent once devcd is ready

stable inclusion
from stable-v4.19.302
commit 49d11d329a92f348d3e6bcac9ebfe05d785f1bb1
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8T1U8

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=49d11d329a92f348d3e6bcac9ebfe05d785f1bb1



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[ Upstream commit af54d778a03853801d681c98c0c2a6c316ef9ca7 ]

dev_coredumpm() creates a devcoredump device and adds it
to the core kernel framework which eventually end up
sending uevent to the user space and later creates a
symbolic link to the failed device. An application
running in userspace may be interested in this symbolic
link to get the name of the failed device.

In a issue scenario, once uevent sent to the user space
it start reading '/sys/class/devcoredump/devcdX/failing_device'
to get the actual name of the device which might not been
created and it is in its path of creation.

To fix this, suppress sending uevent till the failing device
symbolic link gets created and send uevent once symbolic
link is created successfully.

Fixes: 833c9545 ("device coredump: add new device coredump class")
Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/1700232572-25823-1-git-send-email-quic_mojha@quicinc.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com>