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Date: Sun, 20 Jun 2021 18:51:53 +0530 From: Vidya Sagar <vidyas@...dia.com> To: Kishon Vijay Abraham I <kishon@...com> CC: <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Lorenzo Pieralisi" <lorenzo.pieralisi@....com>, Andrew Murray <amurray@...goodpenguin.co.uk>, Bjorn Helgaas <bhelgaas@...gle.com>, "Athani Nadeem Ladkhan" <nadeem@...ence.com>, Tom Joseph <tjoseph@...ence.com>, Manikanta Maddireddy <mmaddireddy@...dia.com>, Om Prakash Singh <omp@...dia.com>, Krishna Thota <kthota@...dia.com> Subject: Re: [PATCH v2 2/5] PCI: endpoint: Replace spinlock with mutex Hi Kishon, Did you get time to look into it? Thanks, Vidya Sagar On 6/11/2021 3:22 PM, Vidya Sagar wrote: > Hi Kishon, > Apologies for bringup it up this late. > I'm wondering if there was any issue which this patch tried to address? > Actually, "The pci_epc_ops is not intended to be invoked from interrupt > context" isn't true in case of Tegra194. We do call > dw_pcie_ep_init_notify() API from threaded irq service routine and it > eventually calls mutext_lock() of pci_epc_get_features() which is > reusulting in the following warning log. > BUG: sleeping function called from invalid context at > kernel/locking/mutex.c: > Would like hear your comments on it. > > Thanks, > Vidya Sagar > > On 2/12/2020 4:55 PM, Kishon Vijay Abraham I wrote: >> External email: Use caution opening links or attachments >> >> >> The pci_epc_ops is not intended to be invoked from interrupt context. >> Hence replace spin_lock_irqsave and spin_unlock_irqrestore with >> mutex_lock and mutex_unlock respectively. >> >> Signed-off-by: Kishon Vijay Abraham I <kishon@...com> >> --- >> drivers/pci/endpoint/pci-epc-core.c | 82 +++++++++++------------------ >> include/linux/pci-epc.h | 6 +-- >> 2 files changed, 34 insertions(+), 54 deletions(-) >> >> diff --git a/drivers/pci/endpoint/pci-epc-core.c >> b/drivers/pci/endpoint/pci-epc-core.c >> index 2f6436599fcb..e51a12ed85bb 100644 >> --- a/drivers/pci/endpoint/pci-epc-core.c >> +++ b/drivers/pci/endpoint/pci-epc-core.c >> @@ -120,7 +120,6 @@ const struct pci_epc_features >> *pci_epc_get_features(struct pci_epc *epc, >> u8 func_no) >> { >> const struct pci_epc_features *epc_features; >> - unsigned long flags; >> >> if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions) >> return NULL; >> @@ -128,9 +127,9 @@ const struct pci_epc_features >> *pci_epc_get_features(struct pci_epc *epc, >> if (!epc->ops->get_features) >> return NULL; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> epc_features = epc->ops->get_features(epc, func_no); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> >> return epc_features; >> } >> @@ -144,14 +143,12 @@ EXPORT_SYMBOL_GPL(pci_epc_get_features); >> */ >> void pci_epc_stop(struct pci_epc *epc) >> { >> - unsigned long flags; >> - >> if (IS_ERR(epc) || !epc->ops->stop) >> return; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> epc->ops->stop(epc); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> } >> EXPORT_SYMBOL_GPL(pci_epc_stop); >> >> @@ -164,7 +161,6 @@ EXPORT_SYMBOL_GPL(pci_epc_stop); >> int pci_epc_start(struct pci_epc *epc) >> { >> int ret; >> - unsigned long flags; >> >> if (IS_ERR(epc)) >> return -EINVAL; >> @@ -172,9 +168,9 @@ int pci_epc_start(struct pci_epc *epc) >> if (!epc->ops->start) >> return 0; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> ret = epc->ops->start(epc); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> >> return ret; >> } >> @@ -193,7 +189,6 @@ int pci_epc_raise_irq(struct pci_epc *epc, u8 >> func_no, >> enum pci_epc_irq_type type, u16 interrupt_num) >> { >> int ret; >> - unsigned long flags; >> >> if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions) >> return -EINVAL; >> @@ -201,9 +196,9 @@ int pci_epc_raise_irq(struct pci_epc *epc, u8 >> func_no, >> if (!epc->ops->raise_irq) >> return 0; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> ret = epc->ops->raise_irq(epc, func_no, type, interrupt_num); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> >> return ret; >> } >> @@ -219,7 +214,6 @@ EXPORT_SYMBOL_GPL(pci_epc_raise_irq); >> int pci_epc_get_msi(struct pci_epc *epc, u8 func_no) >> { >> int interrupt; >> - unsigned long flags; >> >> if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions) >> return 0; >> @@ -227,9 +221,9 @@ int pci_epc_get_msi(struct pci_epc *epc, u8 func_no) >> if (!epc->ops->get_msi) >> return 0; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> interrupt = epc->ops->get_msi(epc, func_no); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> >> if (interrupt < 0) >> return 0; >> @@ -252,7 +246,6 @@ int pci_epc_set_msi(struct pci_epc *epc, u8 >> func_no, u8 interrupts) >> { >> int ret; >> u8 encode_int; >> - unsigned long flags; >> >> if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions || >> interrupts > 32) >> @@ -263,9 +256,9 @@ int pci_epc_set_msi(struct pci_epc *epc, u8 >> func_no, u8 interrupts) >> >> encode_int = order_base_2(interrupts); >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> ret = epc->ops->set_msi(epc, func_no, encode_int); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> >> return ret; >> } >> @@ -281,7 +274,6 @@ EXPORT_SYMBOL_GPL(pci_epc_set_msi); >> int pci_epc_get_msix(struct pci_epc *epc, u8 func_no) >> { >> int interrupt; >> - unsigned long flags; >> >> if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions) >> return 0; >> @@ -289,9 +281,9 @@ int pci_epc_get_msix(struct pci_epc *epc, u8 func_no) >> if (!epc->ops->get_msix) >> return 0; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> interrupt = epc->ops->get_msix(epc, func_no); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> >> if (interrupt < 0) >> return 0; >> @@ -311,7 +303,6 @@ EXPORT_SYMBOL_GPL(pci_epc_get_msix); >> int pci_epc_set_msix(struct pci_epc *epc, u8 func_no, u16 interrupts) >> { >> int ret; >> - unsigned long flags; >> >> if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions || >> interrupts < 1 || interrupts > 2048) >> @@ -320,9 +311,9 @@ int pci_epc_set_msix(struct pci_epc *epc, u8 >> func_no, u16 interrupts) >> if (!epc->ops->set_msix) >> return 0; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> ret = epc->ops->set_msix(epc, func_no, interrupts - 1); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> >> return ret; >> } >> @@ -339,17 +330,15 @@ EXPORT_SYMBOL_GPL(pci_epc_set_msix); >> void pci_epc_unmap_addr(struct pci_epc *epc, u8 func_no, >> phys_addr_t phys_addr) >> { >> - unsigned long flags; >> - >> if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions) >> return; >> >> if (!epc->ops->unmap_addr) >> return; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> epc->ops->unmap_addr(epc, func_no, phys_addr); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> } >> EXPORT_SYMBOL_GPL(pci_epc_unmap_addr); >> >> @@ -367,7 +356,6 @@ int pci_epc_map_addr(struct pci_epc *epc, u8 func_no, >> phys_addr_t phys_addr, u64 pci_addr, size_t size) >> { >> int ret; >> - unsigned long flags; >> >> if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions) >> return -EINVAL; >> @@ -375,9 +363,9 @@ int pci_epc_map_addr(struct pci_epc *epc, u8 func_no, >> if (!epc->ops->map_addr) >> return 0; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> ret = epc->ops->map_addr(epc, func_no, phys_addr, pci_addr, >> size); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> >> return ret; >> } >> @@ -394,8 +382,6 @@ EXPORT_SYMBOL_GPL(pci_epc_map_addr); >> void pci_epc_clear_bar(struct pci_epc *epc, u8 func_no, >> struct pci_epf_bar *epf_bar) >> { >> - unsigned long flags; >> - >> if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions || >> (epf_bar->barno == BAR_5 && >> epf_bar->flags & PCI_BASE_ADDRESS_MEM_TYPE_64)) >> @@ -404,9 +390,9 @@ void pci_epc_clear_bar(struct pci_epc *epc, u8 >> func_no, >> if (!epc->ops->clear_bar) >> return; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> epc->ops->clear_bar(epc, func_no, epf_bar); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> } >> EXPORT_SYMBOL_GPL(pci_epc_clear_bar); >> >> @@ -422,7 +408,6 @@ int pci_epc_set_bar(struct pci_epc *epc, u8 func_no, >> struct pci_epf_bar *epf_bar) >> { >> int ret; >> - unsigned long irq_flags; >> int flags = epf_bar->flags; >> >> if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions || >> @@ -437,9 +422,9 @@ int pci_epc_set_bar(struct pci_epc *epc, u8 func_no, >> if (!epc->ops->set_bar) >> return 0; >> >> - spin_lock_irqsave(&epc->lock, irq_flags); >> + mutex_lock(&epc->lock); >> ret = epc->ops->set_bar(epc, func_no, epf_bar); >> - spin_unlock_irqrestore(&epc->lock, irq_flags); >> + mutex_unlock(&epc->lock); >> >> return ret; >> } >> @@ -460,7 +445,6 @@ int pci_epc_write_header(struct pci_epc *epc, u8 >> func_no, >> struct pci_epf_header *header) >> { >> int ret; >> - unsigned long flags; >> >> if (IS_ERR_OR_NULL(epc) || func_no >= epc->max_functions) >> return -EINVAL; >> @@ -468,9 +452,9 @@ int pci_epc_write_header(struct pci_epc *epc, u8 >> func_no, >> if (!epc->ops->write_header) >> return 0; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> ret = epc->ops->write_header(epc, func_no, header); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> >> return ret; >> } >> @@ -487,8 +471,6 @@ EXPORT_SYMBOL_GPL(pci_epc_write_header); >> */ >> int pci_epc_add_epf(struct pci_epc *epc, struct pci_epf *epf) >> { >> - unsigned long flags; >> - >> if (epf->epc) >> return -EBUSY; >> >> @@ -500,9 +482,9 @@ int pci_epc_add_epf(struct pci_epc *epc, struct >> pci_epf *epf) >> >> epf->epc = epc; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> list_add_tail(&epf->list, &epc->pci_epf); >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> >> return 0; >> } >> @@ -517,15 +499,13 @@ EXPORT_SYMBOL_GPL(pci_epc_add_epf); >> */ >> void pci_epc_remove_epf(struct pci_epc *epc, struct pci_epf *epf) >> { >> - unsigned long flags; >> - >> if (!epc || IS_ERR(epc) || !epf) >> return; >> >> - spin_lock_irqsave(&epc->lock, flags); >> + mutex_lock(&epc->lock); >> list_del(&epf->list); >> epf->epc = NULL; >> - spin_unlock_irqrestore(&epc->lock, flags); >> + mutex_unlock(&epc->lock); >> } >> EXPORT_SYMBOL_GPL(pci_epc_remove_epf); >> >> @@ -604,7 +584,7 @@ __pci_epc_create(struct device *dev, const struct >> pci_epc_ops *ops, >> goto err_ret; >> } >> >> - spin_lock_init(&epc->lock); >> + mutex_init(&epc->lock); >> INIT_LIST_HEAD(&epc->pci_epf); >> ATOMIC_INIT_NOTIFIER_HEAD(&epc->notifier); >> >> diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h >> index 36644ccd32ac..9dd60f2e9705 100644 >> --- a/include/linux/pci-epc.h >> +++ b/include/linux/pci-epc.h >> @@ -88,7 +88,7 @@ struct pci_epc_mem { >> * @mem: address space of the endpoint controller >> * @max_functions: max number of functions that can be configured in >> this EPC >> * @group: configfs group representing the PCI EPC device >> - * @lock: spinlock to protect pci_epc ops >> + * @lock: mutex to protect pci_epc ops >> * @notifier: used to notify EPF of any EPC events (like linkup) >> */ >> struct pci_epc { >> @@ -98,8 +98,8 @@ struct pci_epc { >> struct pci_epc_mem *mem; >> u8 max_functions; >> struct config_group *group; >> - /* spinlock to protect against concurrent access of EP >> controller */ >> - spinlock_t lock; >> + /* mutex to protect against concurrent access of EP controller */ >> + struct mutex lock; >> struct atomic_notifier_head notifier; >> }; >> >> -- >> 2.17.1 >>
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