scsi: libsas: Introduce a _gfp() variant of event notifiers

sas_alloc_event() uses in_interrupt() to decide which allocation should be
used.

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

The in_interrupt() check is also only partially correct, because it fails
to choose the correct code path when just preemption or interrupts are
disabled. For example, as in the following call chain:

  mvsas/mv_sas.c: mvs_work_queue() [process context]
  spin_lock_irqsave(mvs_info::lock, )
    -> libsas/sas_event.c: sas_notify_phy_event()
      -> sas_alloc_event()
        -> in_interrupt() = false
          -> invalid GFP_KERNEL allocation
    -> libsas/sas_event.c: sas_notify_port_event()
      -> sas_alloc_event()
        -> in_interrupt() = false
          -> invalid GFP_KERNEL allocation

Introduce sas_alloc_event_gfp(), sas_notify_port_event_gfp(), and
sas_notify_phy_event_gfp(), which all behave like the non _gfp() variants
but use a caller-passed GFP mask for allocations.

For bisectability, all callers will be modified first to pass GFP context,
then the non _gfp() libsas API variants will be modified to take a gfp_t by
default.

Link: https://lore.kernel.org/r/20210118100955.1761652-4-a.darwish@linutronix.de
Fixes: 1c393b970e0f ("scsi: libsas: Use dynamic alloced work to avoid sas event lost")
Cc: Jason Yan <yanaijie@huawei.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index 3387149502e9..e6a43163ab5b 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -704,5 +704,9 @@ int sas_request_addr(struct Scsi_Host *shost, u8 *addr);
 
 int sas_notify_port_event(struct asd_sas_phy *phy, enum port_event event);
 int sas_notify_phy_event(struct asd_sas_phy *phy, enum phy_event event);
+int sas_notify_port_event_gfp(struct asd_sas_phy *phy, enum port_event event,
+			      gfp_t gfp_flags);
+int sas_notify_phy_event_gfp(struct asd_sas_phy *phy, enum phy_event event,
+			     gfp_t gfp_flags);
 
 #endif /* _SASLIB_H_ */