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Update the softc state of the da driver before releasing the CCB.

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There are contexts where releasing the ccb triggers dastart() to be run
inline. When da was written, there was always a deferral, so it didn't matter
much. Now, with direct dispatch, we can call dastart from the dadone*
routines. If the probe state isn't updated, then dastart will redo things with
stale information. This normally isn't a problem, because we run the probe state
machine once at boot... Except that we also run it for each open of the device,
which means we can have multiple threads racing each other to try to kick off
the probe. However, if we update the state before we release the CCB, we can
avoid the race. While it's needed only for the probewp and proberc* states, do
it everywhere because it won't hurt the other places.

The race here happens because we reprobe dozens of times on boot when drives
have lots of partitions.  We should consider caching this info for 1-2 seconds
to avoid this thundering hurd.

Reviewed by: scottl, ken
Differential Revision: https://reviews.freebsd.org/D22295
This commit is contained in:
Warner Losh 2019-11-11 17:36:52 +00:00
parent fe95666bab
commit dc1c17691e
1 changed files with 10 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
sys/cam/scsi/scsi_da.c
View File

@ -4645,11 +4645,11 @@ dadone_probewp(struct cam_periph *periph, union ccb *done_ccb)
}
free(csio->data_ptr, M_SCSIDA);
xpt_release_ccb(done_ccb);
if ((softc->flags & DA_FLAG_CAN_RC16) != 0)
softc->state = DA_STATE_PROBE_RC16;
else
softc->state = DA_STATE_PROBE_RC;
xpt_release_ccb(done_ccb);
xpt_schedule(periph, priority);
return;
}
@ -4709,8 +4709,8 @@ dadone_proberc(struct cam_periph *periph, union ccb *done_ccb)
*/
if (maxsector == 0xffffffff) {
free(rdcap, M_SCSIDA);
xpt_release_ccb(done_ccb);
softc->state = DA_STATE_PROBE_RC16;
xpt_release_ccb(done_ccb);
xpt_schedule(periph, priority);
return;
}
@ -4816,8 +4816,8 @@ dadone_proberc(struct cam_periph *periph, union ccb *done_ccb)
cam_periph_assert(periph, MA_OWNED);
softc->flags &= ~DA_FLAG_CAN_RC16;
free(rdcap, M_SCSIDA);
xpt_release_ccb(done_ccb);
softc->state = DA_STATE_PROBE_RC;
xpt_release_ccb(done_ccb);
xpt_schedule(periph, priority);
return;
}
@ -4924,14 +4924,14 @@ dadone_proberc(struct cam_periph *periph, union ccb *done_ccb)
dadeleteflag(softc, DA_DELETE_WS10, 1);
dadeleteflag(softc, DA_DELETE_UNMAP, 1);
xpt_release_ccb(done_ccb);
softc->state = DA_STATE_PROBE_LBP;
xpt_release_ccb(done_ccb);
xpt_schedule(periph, priority);
return;
}
xpt_release_ccb(done_ccb);
softc->state = DA_STATE_PROBE_BDC;
xpt_release_ccb(done_ccb);
xpt_schedule(periph, priority);
return;
}
@ -4988,8 +4988,8 @@ dadone_probelbp(struct cam_periph *periph, union ccb *done_ccb)
}
free(lbp, M_SCSIDA);
xpt_release_ccb(done_ccb);
softc->state = DA_STATE_PROBE_BLK_LIMITS;
xpt_release_ccb(done_ccb);
xpt_schedule(periph, priority);
return;
}
@ -5082,8 +5082,8 @@ dadone_probeblklimits(struct cam_periph *periph, union ccb *done_ccb)
}
free(block_limits, M_SCSIDA);
xpt_release_ccb(done_ccb);
softc->state = DA_STATE_PROBE_BDC;
xpt_release_ccb(done_ccb);
xpt_schedule(periph, priority);
return;
}
@ -5183,8 +5183,8 @@ dadone_probebdc(struct cam_periph *periph, union ccb *done_ccb)
}
free(bdc, M_SCSIDA);
xpt_release_ccb(done_ccb);
softc->state = DA_STATE_PROBE_ATA;
xpt_release_ccb(done_ccb);
xpt_schedule(periph, priority);
return;
}
@ -5323,8 +5323,8 @@ dadone_probeata(struct cam_periph *periph, union ccb *done_ccb)
continue_probe = 1;
}
if (continue_probe != 0) {
xpt_release_ccb(done_ccb);
xpt_schedule(periph, priority);
xpt_release_ccb(done_ccb);
return;
} else
daprobedone(periph, done_ccb);
@ -5813,8 +5813,8 @@ dadone_tur(struct cam_periph *periph, union ccb *done_ccb)
/*timeout*/0,
/*getcount_only*/0);
}
xpt_release_ccb(done_ccb);
softc->flags &= ~DA_FLAG_TUR_PENDING;
xpt_release_ccb(done_ccb);
da_periph_release_locked(periph, DA_REF_TUR);
return;
}