From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752762AbaH2A0W (ORCPT ); Thu, 28 Aug 2014 20:26:22 -0400 Received: from p3plsmtps2ded03.prod.phx3.secureserver.net ([208.109.80.60]:50910 "EHLO p3plsmtps2ded03.prod.phx3.secureserver.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752303AbaH2A0S (ORCPT ); Thu, 28 Aug 2014 20:26:18 -0400 x-originating-ip: 72.167.245.219 From: "K. Y. Srinivasan" To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com, jasowang@redhat.com, sitsofe@gmail.com, decui@microsoft.com Cc: "K. Y. Srinivasan" , Subject: [PATCH 1/2] Drivers: hv: vmbus: Cleanup hv_post_message() Date: Thu, 28 Aug 2014 18:29:52 -0700 Message-Id: <1409275793-28511-1-git-send-email-kys@microsoft.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1409275773-28472-1-git-send-email-kys@microsoft.com> References: <1409275773-28472-1-git-send-email-kys@microsoft.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Minimize failures in this function by pre-allocating the buffer for posting messages. The hypercall for posting the message can fail for a number of reasons: 1. Transient resource related issues 2. Buffer alignment 3. Buffer cannot span a page boundry We address issues 2 and 3 by preallocating a per-cpu page for the buffer. Transient resource related failures are handled by retrying by the callers of this function. This patch is based on the investigation done by Dexuan Cui . I would like to thank Sitsofe Wheeler for reporting the issue and helping in debuggging. Signed-off-by: K. Y. Srinivasan Reported-by: Sitsofe Wheeler Cc: --- drivers/hv/hv.c | 27 +++++++++++++++------------ drivers/hv/hyperv_vmbus.h | 4 ++++ 2 files changed, 19 insertions(+), 12 deletions(-) diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c index edfc848..3e4235c 100644 --- a/drivers/hv/hv.c +++ b/drivers/hv/hv.c @@ -138,6 +138,8 @@ int hv_init(void) memset(hv_context.synic_event_page, 0, sizeof(void *) * NR_CPUS); memset(hv_context.synic_message_page, 0, sizeof(void *) * NR_CPUS); + memset(hv_context.post_msg_page, 0, + sizeof(void *) * NR_CPUS); memset(hv_context.vp_index, 0, sizeof(int) * NR_CPUS); memset(hv_context.event_dpc, 0, @@ -217,26 +219,18 @@ int hv_post_message(union hv_connection_id connection_id, enum hv_message_type message_type, void *payload, size_t payload_size) { - struct aligned_input { - u64 alignment8; - struct hv_input_post_message msg; - }; struct hv_input_post_message *aligned_msg; u16 status; - unsigned long addr; if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT) return -EMSGSIZE; - addr = (unsigned long)kmalloc(sizeof(struct aligned_input), GFP_ATOMIC); - if (!addr) - return -ENOMEM; - aligned_msg = (struct hv_input_post_message *) - (ALIGN(addr, HV_HYPERCALL_PARAM_ALIGN)); + hv_context.post_msg_page[get_cpu()]; aligned_msg->connectionid = connection_id; + aligned_msg->reserved = 0; aligned_msg->message_type = message_type; aligned_msg->payload_size = payload_size; memcpy((void *)aligned_msg->payload, payload, payload_size); @@ -244,8 +238,7 @@ int hv_post_message(union hv_connection_id connection_id, status = do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL) & 0xFFFF; - kfree((void *)addr); - + put_cpu(); return status; } @@ -294,6 +287,14 @@ int hv_synic_alloc(void) pr_err("Unable to allocate SYNIC event page\n"); goto err; } + + hv_context.post_msg_page[cpu] = + (void *)get_zeroed_page(GFP_ATOMIC); + + if (hv_context.post_msg_page[cpu] == NULL) { + pr_err("Unable to allocate post msg page\n"); + goto err; + } } return 0; @@ -308,6 +309,8 @@ static void hv_synic_free_cpu(int cpu) free_page((unsigned long)hv_context.synic_event_page[cpu]); if (hv_context.synic_message_page[cpu]) free_page((unsigned long)hv_context.synic_message_page[cpu]); + if (hv_context.post_msg_page[cpu]) + free_page((unsigned long)hv_context.post_msg_page[cpu]); } void hv_synic_free(void) diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h index 22b7507..c386d8d 100644 --- a/drivers/hv/hyperv_vmbus.h +++ b/drivers/hv/hyperv_vmbus.h @@ -515,6 +515,10 @@ struct hv_context { * per-cpu list of the channels based on their CPU affinity. */ struct list_head percpu_list[NR_CPUS]; + /* + * buffer to post messages to the host. + */ + void *post_msg_page[NR_CPUS]; }; extern struct hv_context hv_context; -- 1.7.4.1