Author: cem Date: Tue Oct 13 17:20:47 2015 New Revision: 289232 URL: https://svnweb.freebsd.org/changeset/base/289232
Log: NTB: MFV 113bf1c9: BWD Link Recovery The BWD NTB device will drop the link if an error is encountered on the point-to-point PCI bridge. The link will stay down until all errors are cleared and the link is re-established. On link down, check to see if the error is detected, if so do the necessary housekeeping to try and recover from the error and reestablish the link. There is a potential race between the 2 NTB devices recovering at the same time. If the times are synchronized, the link will not recover and the driver will be stuck in this loop forever. Add a random interval to the recovery time to prevent this race. Authored by: Jon Mason Obtained from: Linux Sponsored by: EMC / Isilon Storage Division Modified: head/sys/dev/ntb/ntb_hw/ntb_hw.c Modified: head/sys/dev/ntb/ntb_hw/ntb_hw.c ============================================================================== --- head/sys/dev/ntb/ntb_hw/ntb_hw.c Tue Oct 13 17:20:05 2015 (r289231) +++ head/sys/dev/ntb/ntb_hw/ntb_hw.c Tue Oct 13 17:20:47 2015 (r289232) @@ -896,6 +896,7 @@ ntb_handle_heartbeat(void *arg) if (rc != 0) device_printf(ntb->device, "Error determining link status\n"); + /* Check to see if a link error is the cause of the link down */ if (ntb->link_status == NTB_LINK_DOWN) { status32 = ntb_reg_read(4, SOC_LTSSMSTATEJMP_OFFSET); @@ -995,7 +996,15 @@ recover_soc_link(void *arg) uint16_t status16; soc_perform_link_restart(ntb); - pause("Link", SOC_LINK_RECOVERY_TIME * hz / 1000); + + /* + * There is a potential race between the 2 NTB devices recovering at + * the same time. If the times are the same, the link will not recover + * and the driver will be stuck in this loop forever. Add a random + * interval to the recovery time to prevent this race. + */ + status32 = arc4random() % SOC_LINK_RECOVERY_TIME; + pause("Link", (SOC_LINK_RECOVERY_TIME + status32) * hz / 1000); status32 = ntb_reg_read(4, SOC_LTSSMSTATEJMP_OFFSET); if ((status32 & SOC_LTSSMSTATEJMP_FORCEDETECT) != 0) @@ -1005,12 +1014,17 @@ recover_soc_link(void *arg) if ((status32 & SOC_IBIST_ERR_OFLOW) != 0) goto retry; + status32 = ntb_reg_read(4, ntb->reg_ofs.lnk_cntl); + if ((status32 & SOC_CNTL_LINK_DOWN) != 0) + goto out; + status16 = ntb_reg_read(2, ntb->reg_ofs.lnk_stat); width = (status16 & NTB_LINK_WIDTH_MASK) >> 4; speed = (status16 & NTB_LINK_SPEED_MASK); if (ntb->link_width != width || ntb->link_speed != speed) goto retry; +out: callout_reset(&ntb->heartbeat_timer, NTB_HB_TIMEOUT * hz, ntb_handle_heartbeat, ntb); return; _______________________________________________ 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"