Subject: Re: [PATCH v7 23/50] powerpc/powernv: Use PE instead of number during setup and release

From: Alexey Kardashevskiy <[email-masked]>
Date: Tue, 17 Nov 2015 16:08:30 +1100

On 11/05/2015 12:12 AM, Gavin Shan wrote:
> In current implementation, the PEs that are allocated or picked
> from the reserved list are identified by PE number. The PE instance
> has to be picked according to the PE number eventually. We have
> same issue when PE is released.
>
> For pnv_ioda_pick_m64_pe() and pnv_ioda_alloc_pe(), this returns
> PE instance so that pnv_ioda_setup_bus_PE() can use the allocated
> or reserved PE instance directly. Also, pnv_ioda_setup_bus_PE()
> returns the reserved/allocated PE instance to be used in subsequent
> patches. On the other hand, pnv_ioda_free_pe() uses PE instance
> (not number) as its argument. No logical changes introduced.
>
> Signed-off-by: Gavin Shan <[email-masked]>
> ---
>   arch/powerpc/platforms/powernv/pci-ioda.c | 81 +++++++++++++++++--------------
>   arch/powerpc/platforms/powernv/pci.h      |  2 +-
>   2 files changed, 46 insertions(+), 37 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index 488e0f8..ae82df1 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -152,7 +152,7 @@ static void pnv_ioda_reserve_pe(struct pnv_phb *phb, int pe_no)
>   	pnv_ioda_init_pe(phb, pe_no);
>   }
>
> -static int pnv_ioda_alloc_pe(struct pnv_phb *phb)
> +static struct pnv_ioda_pe *pnv_ioda_alloc_pe(struct pnv_phb *phb)
>   {
>   	unsigned long pe;
>
> @@ -160,19 +160,20 @@ static int pnv_ioda_alloc_pe(struct pnv_phb *phb)
>   		pe = find_next_zero_bit(phb->ioda.pe_alloc,
>   					phb->ioda.total_pe_num, 0);
>   		if (pe >= phb->ioda.total_pe_num)
> -			return IODA_INVALID_PE;
> +			return NULL;
>   	} while(test_and_set_bit(pe, phb->ioda.pe_alloc));
>
> -	pnv_ioda_init_pe(phb, pe);
> -	return pe;
> +	return pnv_ioda_init_pe(phb, pe);
>   }
>
> -static void pnv_ioda_free_pe(struct pnv_phb *phb, int pe)
> +static void pnv_ioda_free_pe(struct pnv_ioda_pe *pe)
>   {
> -	WARN_ON(phb->ioda.pe_array[pe].pdev);
> +	struct pnv_phb *phb = pe->phb;
> +
> +	WARN_ON(pe->pdev);
>
> -	memset(&phb->ioda.pe_array[pe], 0, sizeof(struct pnv_ioda_pe));
> -	clear_bit(pe, phb->ioda.pe_alloc);
> +	memset(pe, 0, sizeof(struct pnv_ioda_pe));
> +	clear_bit(pe->pe_number, phb->ioda.pe_alloc);
>   }
>
>   /* The default M64 BAR is shared by all PEs */
> @@ -332,7 +333,7 @@ static void pnv_ioda_reserve_m64_pe(struct pci_bus *bus,
>   	}
>   }
>
> -static int pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
> +static struct pnv_ioda_pe *pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
>   {
>   	struct pci_controller *hose = pci_bus_to_host(bus);
>   	struct pnv_phb *phb = hose->private_data;
> @@ -342,7 +343,7 @@ static int pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
>
>   	/* Root bus shouldn't use M64 */
>   	if (pci_is_root_bus(bus))
> -		return IODA_INVALID_PE;
> +		return NULL;
>
>   	/* Allocate bitmap */
>   	size = _ALIGN_UP(phb->ioda.total_pe_num / 8, sizeof(unsigned long));
> @@ -350,7 +351,7 @@ static int pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
>   	if (!pe_alloc) {
>   		pr_warn("%s: Out of memory !\n",
>   			__func__);
> -		return IODA_INVALID_PE;
> +		return NULL;
>   	}
>
>   	/* Figure out reserved PE numbers by the PE */
> @@ -363,7 +364,7 @@ static int pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
>   	 */
>   	if (bitmap_empty(pe_alloc, phb->ioda.total_pe_num)) {
>   		kfree(pe_alloc);
> -		return IODA_INVALID_PE;
> +		return NULL;
>   	}
>
>   	/*
> @@ -409,7 +410,7 @@ static int pnv_ioda_pick_m64_pe(struct pci_bus *bus, bool all)
>   	}
>
>   	kfree(pe_alloc);
> -	return master_pe->pe_number;
> +	return master_pe;
>   }
>
>   static void __init pnv_ioda_parse_m64_window(struct pnv_phb *phb)
> @@ -988,28 +989,26 @@ static void pnv_ioda_setup_same_PE(struct pci_bus *bus, struct pnv_ioda_pe *pe)
>    * subordinate PCI devices and buses. The second type of PE is normally
>    * orgiriated by PCIe-to-PCI bridge or PLX switch downstream ports.
>    */
> -static void pnv_ioda_setup_bus_PE(struct pci_bus *bus, bool all)
> +static struct pnv_ioda_pe *pnv_ioda_setup_bus_PE(struct pci_bus *bus, bool all)
>   {
>   	struct pci_controller *hose = pci_bus_to_host(bus);
>   	struct pnv_phb *phb = hose->private_data;
> -	struct pnv_ioda_pe *pe;
> -	int pe_num = IODA_INVALID_PE;
> +	struct pnv_ioda_pe *pe = NULL;
>
>   	/* Check if PE is determined by M64 */
>   	if (phb->pick_m64_pe)
> -		pe_num = phb->pick_m64_pe(bus, all);
> +		pe = phb->pick_m64_pe(bus, all);
>
>   	/* The PE number isn't pinned by M64 */
> -	if (pe_num == IODA_INVALID_PE)
> -		pe_num = pnv_ioda_alloc_pe(phb);
> +	if (!pe)
> +		pe = pnv_ioda_alloc_pe(phb);
>
> -	if (pe_num == IODA_INVALID_PE) {
> +	if (!pe) {
>   		pr_warning("%s: Not enough PE# available for PCI bus %04x:%02x\n",
>   			__func__, pci_domain_nr(bus), bus->number);
> -		return;
> +		return NULL;
>   	}
>
> -	pe = &phb->ioda.pe_array[pe_num];
>   	pe->flags |= (all ? PNV_IODA_PE_BUS_ALL : PNV_IODA_PE_BUS);
>   	pe->pbus = bus;
>   	pe->pdev = NULL;
> @@ -1018,17 +1017,16 @@ static void pnv_ioda_setup_bus_PE(struct pci_bus *bus, bool all)
>
>   	if (all)
>   		pe_info(pe, "Secondary bus %d..%d associated with PE#%d\n",
> -			bus->busn_res.start, bus->busn_res.end, pe_num);
> +			bus->busn_res.start, bus->busn_res.end, pe->pe_number);
>   	else
>   		pe_info(pe, "Secondary bus %d associated with PE#%d\n",
> -			bus->busn_res.start, pe_num);
> +			bus->busn_res.start, pe->pe_number);
>
>   	if (pnv_ioda_configure_pe(phb, pe)) {
>   		/* XXX What do we do here ? */
> -		if (pe_num)
> -			pnv_ioda_free_pe(phb, pe_num);
> +		pnv_ioda_free_pe(pe);
>   		pe->pbus = NULL;
> -		return;
> +		return NULL;
>   	}
>
>   	/* Associate it with all child devices */
> @@ -1036,6 +1034,8 @@ static void pnv_ioda_setup_bus_PE(struct pci_bus *bus, bool all)
>
>   	/* Put PE to the list */
>   	list_add_tail(&pe->list, &phb->ioda.pe_list);
> +
> +	return pe;
>   }
>
>   static void pnv_ioda_setup_PEs(struct pci_bus *bus)
> @@ -1267,7 +1267,7 @@ static void pnv_ioda_release_vf_PE(struct pci_dev *pdev)
>
>   		pnv_ioda_deconfigure_pe(phb, pe);
>
> -		pnv_ioda_free_pe(phb, pe->pe_number);
> +		pnv_ioda_free_pe(pe);
>   	}
>   }
>
> @@ -1276,6 +1276,7 @@ void pnv_pci_sriov_disable(struct pci_dev *pdev)
>   	struct pci_bus        *bus;
>   	struct pci_controller *hose;
>   	struct pnv_phb        *phb;
> +	struct pnv_ioda_pe    *pe;
>   	struct pci_dn         *pdn;
>   	struct pci_sriov      *iov;
>   	u16                    num_vfs, i;
> @@ -1300,8 +1301,11 @@ void pnv_pci_sriov_disable(struct pci_dev *pdev)
>   		/* Release PE numbers */
>   		if (pdn->m64_single_mode) {
>   			for (i = 0; i < num_vfs; i++) {
> -				if (pdn->pe_num_map[i] != IODA_INVALID_PE)
> -					pnv_ioda_free_pe(phb, pdn->pe_num_map[i]);
> +				if (pdn->pe_num_map[i] == IODA_INVALID_PE)
> +					continue;
> +
> +				pe = &phb->ioda.pe_array[pdn->pe_num_map[i]];
> +				pnv_ioda_free_pe(pe);
>   			}
>   		} else
>   			bitmap_clear(phb->ioda.pe_alloc, *pdn->pe_num_map, num_vfs);
> @@ -1354,9 +1358,8 @@ static void pnv_ioda_setup_vf_PE(struct pci_dev *pdev, u16 num_vfs)
>
>   		if (pnv_ioda_configure_pe(phb, pe)) {
>   			/* XXX What do we do here ? */
> -			if (pe_num)
> -				pnv_ioda_free_pe(phb, pe_num);
>   			pe->pdev = NULL;
> +			pnv_ioda_free_pe(pe);

pnv_ioda_free_pe() does WARN_ON(pdev). Before this patch you would free PE 
first and then reset pe->pdev, now you reset it first, then call 
pnv_ioda_free_pe(). This change is not just about "Use PE instead of number 
during setup and release", is/was that a bug?

And I fail to see when pe->pdev could get initialized in 
pnv_ioda_configure_pe() as pnv_pci_dma_dev_setup() should not be called 
while pnv_ioda_setup_vf_PE() is working.

>   			continue;
>   		}
>
> @@ -1374,6 +1377,7 @@ int pnv_pci_sriov_enable(struct pci_dev *pdev, u16 num_vfs)
>   	struct pci_bus        *bus;
>   	struct pci_controller *hose;
>   	struct pnv_phb        *phb;
> +	struct pnv_ioda_pe    *pe;
>   	struct pci_dn         *pdn;
>   	int                    ret;
>   	u16                    i;
> @@ -1416,11 +1420,13 @@ int pnv_pci_sriov_enable(struct pci_dev *pdev, u16 num_vfs)
>   		/* Calculate available PE for required VFs */
>   		if (pdn->m64_single_mode) {
>   			for (i = 0; i < num_vfs; i++) {
> -				pdn->pe_num_map[i] = pnv_ioda_alloc_pe(phb);
> -				if (pdn->pe_num_map[i] == IODA_INVALID_PE) {
> +				pe = pnv_ioda_alloc_pe(phb);
> +				if (!pe) {
>   					ret = -EBUSY;
>   					goto m64_failed;
>   				}
> +
> +				pdn->pe_num_map[i] = pe->pe_number;
>   			}
>   		} else {
>   			mutex_lock(&phb->ioda.pe_alloc_mutex);
> @@ -1465,8 +1471,11 @@ int pnv_pci_sriov_enable(struct pci_dev *pdev, u16 num_vfs)
>   m64_failed:
>   	if (pdn->m64_single_mode) {
>   		for (i = 0; i < num_vfs; i++) {
> -			if (pdn->pe_num_map[i] != IODA_INVALID_PE)
> -				pnv_ioda_free_pe(phb, pdn->pe_num_map[i]);
> +			if (pdn->pe_num_map[i] == IODA_INVALID_PE)
> +				continue;
> +
> +			pe = &phb->ioda.pe_array[pdn->pe_num_map[i]];
> +			pnv_ioda_free_pe(pe);
>   		}
>   	} else
>   		bitmap_clear(phb->ioda.pe_alloc, *pdn->pe_num_map, num_vfs);
> diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
> index 5df945f..e55ab0e 100644
> --- a/arch/powerpc/platforms/powernv/pci.h
> +++ b/arch/powerpc/platforms/powernv/pci.h
> @@ -105,7 +105,7 @@ struct pnv_phb {
>   	int (*init_m64)(struct pnv_phb *phb);
>   	void (*reserve_m64_pe)(struct pci_bus *bus,
>   			       unsigned long *pe_bitmap, bool all);
> -	int (*pick_m64_pe)(struct pci_bus *bus, bool all);
> +	struct pnv_ioda_pe *(*pick_m64_pe)(struct pci_bus *bus, bool all);
>   	int (*get_pe_state)(struct pnv_phb *phb, int pe_no);
>   	void (*freeze_pe)(struct pnv_phb *phb, int pe_no);
>   	int (*unfreeze_pe)(struct pnv_phb *phb, int pe_no, int opt);
>

-- 
Alexey