Author: royger Date: Tue Dec 15 11:20:20 2015 New Revision: 292258 URL: https://svnweb.freebsd.org/changeset/base/292258
Log: hyperv/kvp: wake up the daemon if it's sleeping due to poll() Without the patch, there is a race condition: when poll() is invoked(), if kvp_globals.daemon_busy is false, the daemon won't be timely woke up, because hv_kvp_send_msg_to_daemon() can't wake up the daemon in this case. Submitted by: Dexuan Cui <de...@microsoft.com> Sponsored by: Microsoft OSTC Reviewed by: delphij, royger MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D4258 Modified: head/sys/dev/hyperv/utilities/hv_kvp.c Modified: head/sys/dev/hyperv/utilities/hv_kvp.c ============================================================================== --- head/sys/dev/hyperv/utilities/hv_kvp.c Tue Dec 15 10:26:47 2015 (r292257) +++ head/sys/dev/hyperv/utilities/hv_kvp.c Tue Dec 15 11:20:20 2015 (r292258) @@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$"); #include <sys/reboot.h> #include <sys/lock.h> #include <sys/taskqueue.h> +#include <sys/selinfo.h> #include <sys/sysctl.h> #include <sys/poll.h> #include <sys/proc.h> @@ -114,6 +115,8 @@ static struct cdev *hv_kvp_dev; static struct hv_kvp_msg *hv_kvp_dev_buf; struct proc *daemon_task; +static struct selinfo hv_kvp_selinfo; + /* * Global state to track and synchronize multiple * KVP transaction requests from the host. @@ -628,6 +631,9 @@ hv_kvp_send_msg_to_daemon(void) /* Send the msg to user via function deamon_read - setting sema */ sema_post(&kvp_globals.dev_sema); + + /* We should wake up the daemon, in case it's doing poll() */ + selwakeup(&hv_kvp_selinfo); } @@ -940,7 +946,7 @@ hv_kvp_dev_daemon_write(struct cdev *dev * for daemon to read. */ static int -hv_kvp_dev_daemon_poll(struct cdev *dev __unused, int events, struct thread *td __unused) +hv_kvp_dev_daemon_poll(struct cdev *dev __unused, int events, struct thread *td) { int revents = 0; @@ -953,6 +959,9 @@ hv_kvp_dev_daemon_poll(struct cdev *dev */ if (kvp_globals.daemon_busy == true) revents = POLLIN; + else + selrecord(td, &hv_kvp_selinfo); + mtx_unlock(&kvp_globals.pending_mutex); return (revents); _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
