Date: Wed, 23 Oct 2013 17:08:50 +0000 (UTC) From: Alexander Motin <mav@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: svn commit: r256988 - stable/9/sys/cam Message-ID: <201310231708.r9NH8oVP061652@svn.freebsd.org>
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Author: mav Date: Wed Oct 23 17:08:50 2013 New Revision: 256988 URL: http://svnweb.freebsd.org/changeset/base/256988 Log: MFC r256188: Close the race on path ID allocation in xpt_bus_register() if two buses are registered simultaneously. Due to topology unlock between the ID allocation and the bus registration there is a chance that two buses may get the same IDs. That is supposed reason of lock assertion panic in CAM during initial bus scanning after new iscsid initiates two sessions same time. Modified: stable/9/sys/cam/cam_xpt.c Directory Properties: stable/9/sys/ (props changed) Modified: stable/9/sys/cam/cam_xpt.c ============================================================================== --- stable/9/sys/cam/cam_xpt.c Wed Oct 23 17:04:09 2013 (r256987) +++ stable/9/sys/cam/cam_xpt.c Wed Oct 23 17:08:50 2013 (r256988) @@ -2450,7 +2450,7 @@ xptsetasyncbusfunc(struct cam_eb *bus, v struct ccb_setasync *csa = (struct ccb_setasync *)arg; xpt_compile_path(&path, /*periph*/NULL, - bus->sim->path_id, + bus->path_id, CAM_TARGET_WILDCARD, CAM_LUN_WILDCARD); xpt_setup_ccb(&cpi.ccb_h, &path, CAM_PRIORITY_NORMAL); @@ -3874,13 +3874,8 @@ xpt_bus_register(struct cam_sim *sim, de /* Couldn't satisfy request */ return (CAM_RESRC_UNAVAIL); } - if (strcmp(sim->sim_name, "xpt") != 0) { - sim->path_id = - xptpathid(sim->sim_name, sim->unit_number, sim->bus_id); - } TAILQ_INIT(&new_bus->et_entries); - new_bus->path_id = sim->path_id; cam_sim_hold(sim); new_bus->sim = sim; timevalclear(&new_bus->last_reset); @@ -3889,6 +3884,8 @@ xpt_bus_register(struct cam_sim *sim, de new_bus->generation = 0; xpt_lock_buses(); + sim->path_id = new_bus->path_id = + xptpathid(sim->sim_name, sim->unit_number, sim->bus_id); old_bus = TAILQ_FIRST(&xsoftc.xpt_busses); while (old_bus != NULL && old_bus->path_id < new_bus->path_id) @@ -3991,8 +3988,8 @@ xptnextfreepathid(void) path_id_t pathid; const char *strval; + mtx_assert(&xsoftc.xpt_topo_lock, MA_OWNED); pathid = 0; - xpt_lock_buses(); bus = TAILQ_FIRST(&xsoftc.xpt_busses); retry: /* Find an unoccupied pathid */ @@ -4001,7 +3998,6 @@ retry: pathid++; bus = TAILQ_NEXT(bus, links); } - xpt_unlock_buses(); /* * Ensure that this pathid is not reserved for @@ -4010,7 +4006,6 @@ retry: if (resource_string_value("scbus", pathid, "at", &strval) == 0) { ++pathid; /* Start the search over */ - xpt_lock_buses(); goto retry; } return (pathid); @@ -4026,6 +4021,8 @@ xptpathid(const char *sim_name, int sim_ pathid = CAM_XPT_PATH_ID; snprintf(buf, sizeof(buf), "%s%d", sim_name, sim_unit); + if (strcmp(buf, "xpt0") == 0 && sim_bus == 0) + return (pathid); i = 0; while ((resource_find_match(&i, &dname, &dunit, "at", buf)) == 0) { if (strcmp(dname, "scbus")) {
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