linux/drivers/s390
Martin Peschke f32c9e03d4 scsi: zfcp: early returns for traces disabled via level
This patch adds early checks to avoid burning CPU cycles on
the assembly of trace entries which would be skipped anyway.

Introduce a static const variable to keep the trace level to check with
debug_level_enabled() in sync with the actual trace emit with
debug_event(). In order not to refactor the SAN tracing too much,
simply use a define instead.

This change is only for the non / semi hot paths,
while the actual (I/O) hot path was already improved earlier:
zfcp_dbf_scsi() is already guarded by its only caller _zfcp_dbf_scsi()
since commit dcd20e2316 ("[SCSI] zfcp: Only collect SCSI debug data for
matching trace levels").
zfcp_dbf_hba_fsf_res() is already guarded by its only caller
zfcp_dbf_hba_fsf_response() since commit 2e261af84c ("[SCSI] zfcp: Only
collect FSF/HBA debug data for matching trace levels").

Signed-off-by: Martin Peschke <mpeschke@linux.vnet.ibm.com>
[maier@linux.vnet.ibm.com: rebase, reword, default level 3 branch prediction]
Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2017-08-10 19:37:03 -04:00
..
block libnvdimm for 4.13 2017-07-07 09:44:06 -07:00
char mm, tree wide: replace __GFP_REPEAT by __GFP_RETRY_MAYFAIL with more useful semantic 2017-07-12 16:26:03 -07:00
cio s390: chp: handle CRW_ERC_INIT for channel-path status change 2017-07-13 11:28:29 +02:00
crypto s390/zcrypt: Fix missing newlines at some debug feature messages. 2017-07-05 07:35:29 +02:00
net drivers: s390: move static and inline before return type 2017-07-12 16:26:04 -07:00
scsi scsi: zfcp: early returns for traces disabled via level 2017-08-10 19:37:03 -04:00
virtio Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2017-05-16 09:24:44 -07:00
Makefile virtio/s390: rename drivers/s390/kvm -> drivers/s390/virtio 2015-07-07 14:27:06 +03:00