On Sun, Aug 19, 2018 at 4:46 PM Lukas Wunner <lukas@xxxxxxxxx> wrote: > > When the PCI hotplug core and its first user, cpqphp, were introduced in > February 2002 with historic commit a8a2069f432c, cpqphp allocated a slot > struct for its internal use plus a hotplug_slot struct to be registered > with the hotplug core and linked the two with pointers: > https://git.kernel.org/tglx/history/c/a8a2069f432c > > Nowadays, the predominant pattern in the tree is to embed ("subclass") > such structures in one another and cast to the containing struct with > container_of(). But it wasn't until July 2002 that container_of() was > introduced with historic commit ec4f214232cf: > https://git.kernel.org/tglx/history/c/ec4f214232cf > > pnv_php, introduced in 2016, did the right thing and embedded struct > hotplug_slot in its internal struct pnv_php_slot, but all other drivers > cargo-culted cpqphp's design and linked separate structs with pointers. > > Embedding structs is preferrable to linking them with pointers because > it requires fewer allocations, thereby reducing overhead and simplifying > error paths. Casting an embedded struct to the containing struct > becomes a cheap subtraction rather than a dereference. And having fewer > pointers reduces the risk of them pointing nowhere either accidentally > or due to an attack. > > Convert all drivers to embed struct hotplug_slot in their internal slot > struct. The "private" pointer in struct hotplug_slot thereby becomes > unused, so drop it. > > Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx> > Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> > Cc: Len Brown <lenb@xxxxxxxxxx> > Cc: Scott Murray <scott@xxxxxxxxxxxx> > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > Cc: Paul Mackerras <paulus@xxxxxxxxx> > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> > Cc: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx> > Cc: Sebastian Ott <sebott@xxxxxxxxxxxxxxxxxx> > Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx> > Cc: Corentin Chary <corentin.chary@xxxxxxxxx> > Cc: Darren Hart <dvhart@xxxxxxxxxxxxx> > Cc: Andy Shevchenko <andy@xxxxxxxxxxxxx> > --- > drivers/pci/hotplug/acpiphp.h | 9 ++- > drivers/pci/hotplug/acpiphp_core.c | 28 +++----- > drivers/pci/hotplug/acpiphp_ibm.c | 2 +- > drivers/pci/hotplug/cpci_hotplug.h | 9 ++- > drivers/pci/hotplug/cpci_hotplug_core.c | 37 ++++------ > drivers/pci/hotplug/cpci_hotplug_pci.c | 6 +- > drivers/pci/hotplug/cpqphp.h | 9 ++- > drivers/pci/hotplug/cpqphp_core.c | 37 ++++------ > drivers/pci/hotplug/cpqphp_ctrl.c | 2 - > drivers/pci/hotplug/ibmphp.h | 7 +- > drivers/pci/hotplug/ibmphp_core.c | 92 +++++++++++-------------- > drivers/pci/hotplug/ibmphp_ebda.c | 37 +++------- > drivers/pci/hotplug/pciehp.h | 11 ++- > drivers/pci/hotplug/pciehp_core.c | 37 ++++------ > drivers/pci/hotplug/pciehp_ctrl.c | 4 +- > drivers/pci/hotplug/pciehp_hpc.c | 8 +-- > drivers/pci/hotplug/pnv_php.c | 9 ++- > drivers/pci/hotplug/rpaphp.h | 7 +- > drivers/pci/hotplug/rpaphp_core.c | 14 ++-- > drivers/pci/hotplug/rpaphp_slot.c | 15 ++-- > drivers/pci/hotplug/s390_pci_hpc.c | 30 ++++---- > drivers/pci/hotplug/sgi_hotplug.c | 52 ++++++-------- > drivers/pci/hotplug/shpchp.h | 6 +- > drivers/pci/hotplug/shpchp_core.c | 17 ++--- > drivers/platform/x86/asus-wmi.c | 26 +++---- > drivers/platform/x86/eeepc-laptop.c | 30 ++++---- > include/linux/pci_hotplug.h | 3 - > 27 files changed, 223 insertions(+), 321 deletions(-) Good cleanup. Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
