EDAC/mc: Change mci device removal to use put_device()

There are dimm and csrow devices linked to the mci device esp. to show
up in sysfs. It must be granted that children devices are removed before
its mci parent. Thus, the release functions must be called in the
correct order and may not miss any child before releasing its parent. In
the current implementation this is only granted by the correct order of
release functions.

A much better approach is to use put_device() that releases the device
only after all users are gone. It is the recommended way to release a
device and free its memory. The function uses the device's refcount and
only frees it if there are no users of it anymore such as children.

So implement a mci_release() function to remove mci devices, use
put_device() to free them and early initialize the mci device right
after its struct has been allocated.

Change the release function so that it can be universally used no
matter if the device is registered or not. Since subsequent dimm
and csrow sysfs links are implemented as children devices, their
refcounts will keep the parent mci device from being removed as long
as sysfs entries exist and until all users have been unregistered in
edac_remove_sysfs_mci_device().

Remove edac_unregister_sysfs() and merge mci sysfs removal into
edac_remove_sysfs_mci_device(). There is only a single instance now that
removes the sysfs entries. The function can now be used in the error
paths for cleanup.

Also, create device release functions for all involved devices
(dev->release), remove device_type release functions (dev_type->
release) and also use dev->init_name instead of dev_set_name().

 [ bp: Massage commit message and comments. ]

Signed-off-by: Robert Richter <rrichter@marvell.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Link: https://lkml.kernel.org/r/20200212120340.4764-5-rrichter@marvell.com

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 69e0d90460e6..64785e644482 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -278,6 +278,12 @@ void *edac_align_ptr(void **p, unsigned int size, int n_elems)
 
 static void _edac_mc_free(struct mem_ctl_info *mci)
 {
+	put_device(&mci->dev);
+}
+
+static void mci_release(struct device *dev)
+{
+	struct mem_ctl_info *mci = container_of(dev, struct mem_ctl_info, dev);
 	struct csrow_info *csr;
 	int i, chn, row;
 
@@ -371,6 +377,9 @@ struct mem_ctl_info *edac_mc_alloc(unsigned int mc_num,
 	if (mci == NULL)
 		return NULL;
 
+	mci->dev.release = mci_release;
+	device_initialize(&mci->dev);
+
 	/* Adjust pointers so they point within the memory we just allocated
 	 * rather than an imaginary chunk of memory located at address 0.
 	 */
@@ -505,9 +514,6 @@ void edac_mc_free(struct mem_ctl_info *mci)
 {
 	edac_dbg(1, "\n");
 
-	if (device_is_registered(&mci->dev))
-		edac_unregister_sysfs(mci);
-
 	_edac_mc_free(mci);
 }
 EXPORT_SYMBOL_GPL(edac_mc_free);