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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 29 Jan 2019 11:06:26 -0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x0TB6O9A61341836 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 29 Jan 2019 11:06:24 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 18FB0A404D; Tue, 29 Jan 2019 11:06:24 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id ED0FEA4051; Tue, 29 Jan 2019 11:06:21 +0000 (GMT) Received: from vajain21.in.ibm.com (unknown [9.109.223.28]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 29 Jan 2019 11:06:21 +0000 (GMT) From: Vaibhav Jain To: linuxppc-dev@lists.ozlabs.org, Frederic Barrat Subject: [RESEND PATCH v3] cxl: Wrap iterations over afu slices inside 'afu_list_lock' Date: Tue, 29 Jan 2019 16:36:18 +0530 X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19012911-0016-0000-0000-0000024D42AF X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19012911-0017-0000-0000-000032A74527 Message-Id: <20190129110618.13481-1-vaibhav@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-01-29_08:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1901290086 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Philippe Bergheaud , Christophe Lombard , stable@vger.kernel.org, Alastair D'Silva , Andrew Donnellan , Vaibhav Jain , Christophe Lombard Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Within cxl module, iteration over array 'adapter->afu' may be racy at few points as it might be simultaneously read during an EEH and its contents being set to NULL while driver is being unloaded or unbound from the adapter. This might result in a NULL pointer to 'struct afu' being de-referenced during an EEH thereby causing a kernel oops. This patch fixes this by making sure that all access to the array 'adapter->afu' is wrapped within the context of spin-lock 'adapter->afu_list_lock'. Cc: stable@vger.kernel.org Fixes: 9e8df8a2196("cxl: EEH support") Acked-by: Andrew Donnellan Acked-by: Frederic Barrat Acked-by: Christophe Lombard Signed-off-by: Vaibhav Jain --- Changelog: Resend: * Fixed the reference to 'adapter->afu' in patch description. [Andrew] * Added the 'Fixes' tag and marked the patch to stable v3: * Updated a slice loop in cxl_pci_error_detectected() to ignore NULL slices [Fred] * Added a NULL AFU check in cxl_pci_slot_reset() [Fred] v2: * Fixed a wrong comparison of non-null pointer [Fred] * Moved a call to cxl_vphb_error_detected() within a branch that checks for not null AFU pointer in 'adapter->slices' [Fred] * Removed a misleading comment in code. --- drivers/misc/cxl/guest.c | 2 ++ drivers/misc/cxl/pci.c | 39 ++++++++++++++++++++++++++++++--------- 2 files changed, 32 insertions(+), 9 deletions(-) diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c index 5d28d9e454f5..08f4a512afad 100644 --- a/drivers/misc/cxl/guest.c +++ b/drivers/misc/cxl/guest.c @@ -267,6 +267,7 @@ static int guest_reset(struct cxl *adapter) int i, rc; pr_devel("Adapter reset request\n"); + spin_lock(&adapter->afu_list_lock); for (i = 0; i < adapter->slices; i++) { if ((afu = adapter->afu[i])) { pci_error_handlers(afu, CXL_ERROR_DETECTED_EVENT, @@ -283,6 +284,7 @@ static int guest_reset(struct cxl *adapter) pci_error_handlers(afu, CXL_RESUME_EVENT, 0); } } + spin_unlock(&adapter->afu_list_lock); return rc; } diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c index c79ba1c699ad..300531d6136f 100644 --- a/drivers/misc/cxl/pci.c +++ b/drivers/misc/cxl/pci.c @@ -1805,7 +1805,7 @@ static pci_ers_result_t cxl_vphb_error_detected(struct cxl_afu *afu, /* There should only be one entry, but go through the list * anyway */ - if (afu->phb == NULL) + if (afu == NULL || afu->phb == NULL) return result; list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) { @@ -1832,7 +1832,8 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev, { struct cxl *adapter = pci_get_drvdata(pdev); struct cxl_afu *afu; - pci_ers_result_t result = PCI_ERS_RESULT_NEED_RESET, afu_result; + pci_ers_result_t result = PCI_ERS_RESULT_NEED_RESET; + pci_ers_result_t afu_result = PCI_ERS_RESULT_NEED_RESET; int i; /* At this point, we could still have an interrupt pending. @@ -1843,6 +1844,7 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev, /* If we're permanently dead, give up. */ if (state == pci_channel_io_perm_failure) { + spin_lock(&adapter->afu_list_lock); for (i = 0; i < adapter->slices; i++) { afu = adapter->afu[i]; /* @@ -1851,6 +1853,7 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev, */ cxl_vphb_error_detected(afu, state); } + spin_unlock(&adapter->afu_list_lock); return PCI_ERS_RESULT_DISCONNECT; } @@ -1932,11 +1935,17 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev, * * In slot_reset, free the old resources and allocate new ones. * * In resume, clear the flag to allow things to start. */ + + /* Make sure no one else changes the afu list */ + spin_lock(&adapter->afu_list_lock); + for (i = 0; i < adapter->slices; i++) { afu = adapter->afu[i]; - afu_result = cxl_vphb_error_detected(afu, state); + if (afu == NULL) + continue; + afu_result = cxl_vphb_error_detected(afu, state); cxl_context_detach_all(afu); cxl_ops->afu_deactivate_mode(afu, afu->current_mode); pci_deconfigure_afu(afu); @@ -1948,6 +1957,7 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev, (result == PCI_ERS_RESULT_NEED_RESET)) result = PCI_ERS_RESULT_NONE; } + spin_unlock(&adapter->afu_list_lock); /* should take the context lock here */ if (cxl_adapter_context_lock(adapter) != 0) @@ -1980,14 +1990,18 @@ static pci_ers_result_t cxl_pci_slot_reset(struct pci_dev *pdev) */ cxl_adapter_context_unlock(adapter); + spin_lock(&adapter->afu_list_lock); for (i = 0; i < adapter->slices; i++) { afu = adapter->afu[i]; + if (afu == NULL) + continue; + if (pci_configure_afu(afu, adapter, pdev)) - goto err; + goto err_unlock; if (cxl_afu_select_best_mode(afu)) - goto err; + goto err_unlock; if (afu->phb == NULL) continue; @@ -1999,16 +2013,16 @@ static pci_ers_result_t cxl_pci_slot_reset(struct pci_dev *pdev) ctx = cxl_get_context(afu_dev); if (ctx && cxl_release_context(ctx)) - goto err; + goto err_unlock; ctx = cxl_dev_context_init(afu_dev); if (IS_ERR(ctx)) - goto err; + goto err_unlock; afu_dev->dev.archdata.cxl_ctx = ctx; if (cxl_ops->afu_check_and_enable(afu)) - goto err; + goto err_unlock; afu_dev->error_state = pci_channel_io_normal; @@ -2029,8 +2043,13 @@ static pci_ers_result_t cxl_pci_slot_reset(struct pci_dev *pdev) result = PCI_ERS_RESULT_DISCONNECT; } } + + spin_unlock(&adapter->afu_list_lock); return result; +err_unlock: + spin_unlock(&adapter->afu_list_lock); + err: /* All the bits that happen in both error_detected and cxl_remove * should be idempotent, so we don't need to worry about leaving a mix @@ -2051,10 +2070,11 @@ static void cxl_pci_resume(struct pci_dev *pdev) * This is not the place to be checking if everything came back up * properly, because there's no return value: do that in slot_reset. */ + spin_lock(&adapter->afu_list_lock); for (i = 0; i < adapter->slices; i++) { afu = adapter->afu[i]; - if (afu->phb == NULL) + if (afu == NULL || afu->phb == NULL) continue; list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) { @@ -2063,6 +2083,7 @@ static void cxl_pci_resume(struct pci_dev *pdev) afu_dev->driver->err_handler->resume(afu_dev); } } + spin_unlock(&adapter->afu_list_lock); } static const struct pci_error_handlers cxl_err_handler = { -- 2.20.1