From 8b7ac2bb07bbadb0636f21f51564e6d363bb6d20 Mon Sep 17 00:00:00 2001 From: Vasu Dev Date: Fri, 8 Oct 2010 17:12:31 -0700 Subject: [PATCH] [SCSI] libfc: possible race could panic system due to NULL fsp->cmd It is unlikely but in case if it hits then it would cause panic due to null cmd ptr, so far only one instance seen recently with ESX though this was introduced long ago with this commit:- commit c1ecb90a66c5afc7cc5c9349f9c3714eef4a5cfb Author: Chris Leech Date: Thu Dec 10 09:59:26 2009 -0800 [SCSI] libfc: reduce hold time on SCSI host lock Currently fsp->cmd is set to NULL w/o scsi_queue_lock before dequeuing from scsi_pkt_queue and that could cause NULL fsp->cmd in fc_fcp_cleanup_each_cmd for cmd completing with fsp->cmd = NULL after fc_fcp_cleanup_each_cmd taken reference. No need to set fsp->cmd to NULL as this is also protected by fc_fcp_lock_pkt(), for above race the fc_fcp_lock_pkt() in fc_fcp_cleanup_each_cmd() will fail as that cmd is already done. Mike mentioned same issue at http://www.open-fcoe.org/pipermail/devel/2010-September/010533.html Similarly moved sc_cmd->SCp.ptr = NULL under scsi_queue_lock so that scsi abort error handler won't abort on completed cmds. Signed-off-by: Vasu Dev Signed-off-by: Robert Love Signed-off-by: James Bottomley --- drivers/scsi/libfc/fc_fcp.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) diff --git a/drivers/scsi/libfc/fc_fcp.c b/drivers/scsi/libfc/fc_fcp.c index 43866e6d0bf2..e340373b509b 100644 --- a/drivers/scsi/libfc/fc_fcp.c +++ b/drivers/scsi/libfc/fc_fcp.c @@ -58,8 +58,7 @@ struct kmem_cache *scsi_pkt_cachep; #define FC_SRB_WRITE (1 << 0) /* - * The SCp.ptr should be tested and set under the host lock. NULL indicates - * that the command has been retruned to the scsi layer. + * The SCp.ptr should be tested and set under the scsi_pkt_queue lock */ #define CMD_SP(Cmnd) ((struct fc_fcp_pkt *)(Cmnd)->SCp.ptr) #define CMD_ENTRY_STATUS(Cmnd) ((Cmnd)->SCp.have_data_in) @@ -1880,8 +1879,6 @@ static void fc_io_compl(struct fc_fcp_pkt *fsp) lport = fsp->lp; si = fc_get_scsi_internal(lport); - if (!fsp->cmd) - return; /* * if can_queue ramp down is done then try can_queue ramp up @@ -1891,11 +1888,6 @@ static void fc_io_compl(struct fc_fcp_pkt *fsp) fc_fcp_can_queue_ramp_up(lport); sc_cmd = fsp->cmd; - fsp->cmd = NULL; - - if (!sc_cmd->SCp.ptr) - return; - CMD_SCSI_STATUS(sc_cmd) = fsp->cdb_status; switch (fsp->status_code) { case FC_COMPLETE: @@ -1976,8 +1968,8 @@ static void fc_io_compl(struct fc_fcp_pkt *fsp) spin_lock_irqsave(&si->scsi_queue_lock, flags); list_del(&fsp->list); - spin_unlock_irqrestore(&si->scsi_queue_lock, flags); sc_cmd->SCp.ptr = NULL; + spin_unlock_irqrestore(&si->scsi_queue_lock, flags); sc_cmd->scsi_done(sc_cmd); /* release ref from initial allocation in queue command */ @@ -1995,6 +1987,7 @@ int fc_eh_abort(struct scsi_cmnd *sc_cmd) { struct fc_fcp_pkt *fsp; struct fc_lport *lport; + struct fc_fcp_internal *si; int rc = FAILED; unsigned long flags; @@ -2004,7 +1997,8 @@ int fc_eh_abort(struct scsi_cmnd *sc_cmd) else if (!lport->link_up) return rc; - spin_lock_irqsave(lport->host->host_lock, flags); + si = fc_get_scsi_internal(lport); + spin_lock_irqsave(&si->scsi_queue_lock, flags); fsp = CMD_SP(sc_cmd); if (!fsp) { /* command completed while scsi eh was setting up */ @@ -2013,7 +2007,7 @@ int fc_eh_abort(struct scsi_cmnd *sc_cmd) } /* grab a ref so the fsp and sc_cmd cannot be relased from under us */ fc_fcp_pkt_hold(fsp); - spin_unlock_irqrestore(lport->host->host_lock, flags); + spin_unlock_irqrestore(&si->scsi_queue_lock, flags); if (fc_fcp_lock_pkt(fsp)) { /* completed while we were waiting for timer to be deleted */ -- 2.34.1