From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp03.au.ibm.com (e23smtp03.au.ibm.com [202.81.31.145]) (using TLSv1.2 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3A8C31A02EF for ; Fri, 11 Mar 2016 10:19:55 +1100 (AEDT) Received: from localhost by e23smtp03.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 11 Mar 2016 09:19:53 +1000 Received: from d23relay10.au.ibm.com (d23relay10.au.ibm.com [9.190.26.77]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 4BA032BB0054 for ; Fri, 11 Mar 2016 10:19:51 +1100 (EST) Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay10.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u2ANJh2M5636596 for ; Fri, 11 Mar 2016 10:19:51 +1100 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u2ANJI7n009212 for ; Fri, 11 Mar 2016 10:19:19 +1100 Date: Fri, 11 Mar 2016 10:18:23 +1100 From: Gavin Shan To: Benjamin Herrenschmidt Cc: "Guilherme G. Piccoli" , linuxppc-dev@lists.ozlabs.org, linux-pci@vger.kernel.org, mpe@ellerman.id.au, paulus@samba.org, imunsie@au1.ibm.com, mikey@neuling.org, andrew.donnellan@au1.ibm.com, gwshan@linux.vnet.ibm.com, bhelgaas@google.com Subject: Re: [PATCH] powerpc/pci: Reuse PHB number on pci_controller add if available Message-ID: <20160310231823.GA5270@gwshan> Reply-To: Gavin Shan References: <1457633505-19857-1-git-send-email-gpiccoli@linux.vnet.ibm.com> <1457633505-19857-2-git-send-email-gpiccoli@linux.vnet.ibm.com> <1457645698.24238.76.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: <1457645698.24238.76.camel@kernel.crashing.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Mar 11, 2016 at 08:34:58AM +1100, Benjamin Herrenschmidt wrote: >On Thu, 2016-03-10 at 15:11 -0300, Guilherme G. Piccoli wrote: >> The domain/PHB field of PCI addresses has its value obtained from a >> global variable, incremented each time a new domain (represented by >> struct pci_controller) is added on the system. The domain addition >> process happens during boot or due to PCI device hotplug. > >I'd rather we use a fixed numbering for domains, for example, under >OPAL, use the opal-id, under phyp, there is also a number in the DT we >can use (forgot what it's called) etc... > guest on phyp has something like below: ibm,fw-phb-id = <0x8000000 0x20000200>; However, PowerKVM guest doesn't have it. I guess it's a problem, right? Thanks, Gavin >> As recent kernels are using predictable naming for network >> interfaces, >> the network stack is more tied to PCI naming. This can be a problem >> in >> hotplug scenarios, because PCI addresses will change if a device is >> removed and then re-added. This situation seems unusual, but it can >> happen if a user wants to replace a NIC without rebooting the >> machine, >> for example. >> >> This patch changes the way PCI domain values are generated: the >> global >> variable is no longer used; instead, a list is introduced, containing >> a flag that indicates whenever a domain is in use or was released, >> for >> example by a PCI hotplug remove. If the new PHB being added finds a >> free domain, it will use its number; otherwise a new number is >> generated incrementing the higher domain value present on the system. >> No functional changes were introduced. >> >> Signed-off-by: Guilherme G. Piccoli >> --- >>  arch/powerpc/kernel/pci-common.c | 47 >> +++++++++++++++++++++++++++++++++++++--- >>  1 file changed, 44 insertions(+), 3 deletions(-) >> >> diff --git a/arch/powerpc/kernel/pci-common.c >> b/arch/powerpc/kernel/pci-common.c >> index 0f7a60f..6eac0dd 100644 >> --- a/arch/powerpc/kernel/pci-common.c >> +++ b/arch/powerpc/kernel/pci-common.c >> @@ -44,8 +44,12 @@ >>  static DEFINE_SPINLOCK(hose_spinlock); >>  LIST_HEAD(hose_list); >>   >> -/* XXX kill that some day ... */ >> -static int global_phb_number; /* Global phb counter >> */ >> +/* Global PHB counter list */ >> +struct global_phb_number { >> + bool used; >> + struct list_head node; >> +}; >> +LIST_HEAD(global_phb_number_list); >>   >>  /* ISA Memory physical address */ >>  resource_size_t isa_mem_base; >> @@ -64,6 +68,42 @@ struct dma_map_ops *get_pci_dma_ops(void) >>  } >>  EXPORT_SYMBOL(get_pci_dma_ops); >>   >> +static int get_phb_number(void) >> +{ >> + struct global_phb_number *ptr; >> + int latest_number = 0; >> + >> + list_for_each_entry(ptr, &global_phb_number_list, node) { >> + if (!ptr->used) { >> + ptr->used = true; >> + return latest_number; >> + } >> + latest_number++; >> + } >> + >> + ptr = zalloc_maybe_bootmem(sizeof(struct global_phb_number), >> GFP_KERNEL); >> + BUG_ON(ptr == NULL); >> + >> + ptr->used = true; >> + list_add_tail(&ptr->node, &global_phb_number_list); >> + >> + return latest_number; >> +} >> + >> +static void release_phb_number(int phb_number) >> +{ >> + struct global_phb_number *ptr; >> + int current_number = 0; >> + >> + list_for_each_entry(ptr, &global_phb_number_list, node) { >> + if (current_number == phb_number) { >> + ptr->used = false; >> + return; >> + } >> + current_number++; >> + } >> +} >> + >>  struct pci_controller *pcibios_alloc_controller(struct device_node >> *dev) >>  { >>   struct pci_controller *phb; >> @@ -72,7 +112,7 @@ struct pci_controller >> *pcibios_alloc_controller(struct device_node *dev) >>   if (phb == NULL) >>   return NULL; >>   spin_lock(&hose_spinlock); >> - phb->global_number = global_phb_number++; >> + phb->global_number = get_phb_number(); >>   list_add_tail(&phb->list_node, &hose_list); >>   spin_unlock(&hose_spinlock); >>   phb->dn = dev; >> @@ -94,6 +134,7 @@ EXPORT_SYMBOL_GPL(pcibios_alloc_controller); >>  void pcibios_free_controller(struct pci_controller *phb) >>  { >>   spin_lock(&hose_spinlock); >> + release_phb_number(phb->global_number); >>   list_del(&phb->list_node); >>   spin_unlock(&hose_spinlock); >>   >