From 420f0e2c5d8338b42047c58f055cdb944685ead7 Mon Sep 17 00:00:00 2001 From: Jeremy Kerr Date: Tue, 29 Sep 2015 12:14:16 +0800 Subject: [PATCH] discover/ipmi: Use advisory locking on ipmi device The ipmi module is shared between pb-config and pb-discover. During system initilisation, we're likely to have a few invocations of pb-config running, as well as pb-discover starting. We may have multiple potential concurrent accesses to the ipmi device node. To avoid problems, this change introduces a fcntl lock on the device node. Signed-off-by: Jeremy Kerr --- discover/ipmi.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) diff --git a/discover/ipmi.c b/discover/ipmi.c index 710a47d..54d4e06 100644 --- a/discover/ipmi.c +++ b/discover/ipmi.c @@ -107,11 +107,21 @@ int ipmi_transaction(struct ipmi *ipmi, uint8_t netfn, uint8_t cmd, { struct timeval start, now, delta; struct pollfd pollfds[1]; + struct flock lock; int expired_ms, rc; + memset(&lock, 0, sizeof(lock)); + lock.l_type = F_WRLCK; + lock.l_whence = SEEK_SET; + rc = fcntl(ipmi->fd, F_SETLKW, &lock); + if (rc == -1) { + pb_log("IPMI: error locking IPMI device: %m\n"); + return rc; + } + rc = ipmi_send(ipmi, netfn, cmd, req_buf, req_len); if (rc) - return rc; + goto out; pollfds[0].fd = ipmi->fd; pollfds[0].events = POLLIN; @@ -132,11 +142,13 @@ int ipmi_transaction(struct ipmi *ipmi, uint8_t netfn, uint8_t cmd, if (rc == 0) { pb_log("IPMI: timeout waiting for response " "(netfn %d, cmd %d)\n", netfn, cmd); + rc = -1; break; } if (!(pollfds[0].revents & POLLIN)) { pb_log("IPMI: unexpected fd status from poll?\n"); + rc = -1; break; } @@ -156,17 +168,23 @@ int ipmi_transaction(struct ipmi *ipmi, uint8_t netfn, uint8_t cmd, expired_ms = (delta.tv_sec * 1000) + (delta.tv_usec / 1000); - if (expired_ms >= timeout_ms) + if (expired_ms >= timeout_ms) { + rc = -1; break; + } } } else { pb_debug("IPMI: netfn(%x->%x), cmd(%x->%x)\n", netfn, resp_netfn, cmd, resp_cmd); - return 0; + rc = 0; + goto out; } } - return -1; +out: + lock.l_type = F_UNLCK; + fcntl(ipmi->fd, F_SETLKW, &lock); + return rc ? -1 : 0; } static int ipmi_destroy(void *p) -- 2.39.2