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Subject[PATCH 1/3] nvme/scsi: Remove power management support
Date
As far as I can tell, there is basically nothing correct about this
code. It misinterprets npss (off-by-one). It hardcodes a bunch of
power states, which is nonsense, because they're all just indices
into a table that software needs to parse. It completely ignores
the distinction between operational and non-operational states.
And, until 4.8, if all of the above magically succeeded, it would
dereference a NULL pointer and OOPS.

Since this code appears to be useless, just delete it.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
drivers/nvme/host/scsi.c | 74 ++----------------------------------------------
1 file changed, 3 insertions(+), 71 deletions(-)

diff --git a/drivers/nvme/host/scsi.c b/drivers/nvme/host/scsi.c
index e947e298a737..44009105f8c8 100644
--- a/drivers/nvme/host/scsi.c
+++ b/drivers/nvme/host/scsi.c
@@ -72,15 +72,6 @@ static int sg_version_num = 30534; /* 2 digits for each component */
#define ALL_LUNS_RETURNED 0x02
#define ALL_WELL_KNOWN_LUNS_RETURNED 0x01
#define RESTRICTED_LUNS_RETURNED 0x00
-#define NVME_POWER_STATE_START_VALID 0x00
-#define NVME_POWER_STATE_ACTIVE 0x01
-#define NVME_POWER_STATE_IDLE 0x02
-#define NVME_POWER_STATE_STANDBY 0x03
-#define NVME_POWER_STATE_LU_CONTROL 0x07
-#define POWER_STATE_0 0
-#define POWER_STATE_1 1
-#define POWER_STATE_2 2
-#define POWER_STATE_3 3
#define DOWNLOAD_SAVE_ACTIVATE 0x05
#define DOWNLOAD_SAVE_DEFER_ACTIVATE 0x0E
#define ACTIVATE_DEFERRED_MICROCODE 0x0F
@@ -1229,64 +1220,6 @@ static void nvme_trans_fill_read_cap(u8 *response, struct nvme_id_ns *id_ns,

/* Start Stop Unit Helper Functions */

-static int nvme_trans_power_state(struct nvme_ns *ns, struct sg_io_hdr *hdr,
- u8 pc, u8 pcmod, u8 start)
-{
- int res;
- int nvme_sc;
- struct nvme_id_ctrl *id_ctrl;
- int lowest_pow_st; /* max npss = lowest power consumption */
- unsigned ps_desired = 0;
-
- nvme_sc = nvme_identify_ctrl(ns->ctrl, &id_ctrl);
- res = nvme_trans_status_code(hdr, nvme_sc);
- if (res)
- return res;
-
- lowest_pow_st = max(POWER_STATE_0, (int)(id_ctrl->npss - 1));
- kfree(id_ctrl);
-
- switch (pc) {
- case NVME_POWER_STATE_START_VALID:
- /* Action unspecified if POWER CONDITION MODIFIER != 0 */
- if (pcmod == 0 && start == 0x1)
- ps_desired = POWER_STATE_0;
- if (pcmod == 0 && start == 0x0)
- ps_desired = lowest_pow_st;
- break;
- case NVME_POWER_STATE_ACTIVE:
- /* Action unspecified if POWER CONDITION MODIFIER != 0 */
- if (pcmod == 0)
- ps_desired = POWER_STATE_0;
- break;
- case NVME_POWER_STATE_IDLE:
- /* Action unspecified if POWER CONDITION MODIFIER != [0,1,2] */
- if (pcmod == 0x0)
- ps_desired = POWER_STATE_1;
- else if (pcmod == 0x1)
- ps_desired = POWER_STATE_2;
- else if (pcmod == 0x2)
- ps_desired = POWER_STATE_3;
- break;
- case NVME_POWER_STATE_STANDBY:
- /* Action unspecified if POWER CONDITION MODIFIER != [0,1] */
- if (pcmod == 0x0)
- ps_desired = max(POWER_STATE_0, (lowest_pow_st - 2));
- else if (pcmod == 0x1)
- ps_desired = max(POWER_STATE_0, (lowest_pow_st - 1));
- break;
- case NVME_POWER_STATE_LU_CONTROL:
- default:
- res = nvme_trans_completion(hdr, SAM_STAT_CHECK_CONDITION,
- ILLEGAL_REQUEST, SCSI_ASC_INVALID_CDB,
- SCSI_ASCQ_CAUSE_NOT_REPORTABLE);
- break;
- }
- nvme_sc = nvme_set_features(ns->ctrl, NVME_FEAT_POWER_MGMT, ps_desired, 0,
- NULL);
- return nvme_trans_status_code(hdr, nvme_sc);
-}
-
static int nvme_trans_send_activate_fw_cmd(struct nvme_ns *ns, struct sg_io_hdr *hdr,
u8 buffer_id)
{
@@ -2235,11 +2168,10 @@ static int nvme_trans_synchronize_cache(struct nvme_ns *ns,
static int nvme_trans_start_stop(struct nvme_ns *ns, struct sg_io_hdr *hdr,
u8 *cmd)
{
- u8 immed, pcmod, pc, no_flush, start;
+ u8 immed, pcmod, no_flush, start;

immed = cmd[1] & 0x01;
pcmod = cmd[3] & 0x0f;
- pc = (cmd[4] & 0xf0) >> 4;
no_flush = cmd[4] & 0x04;
start = cmd[4] & 0x01;

@@ -2254,8 +2186,8 @@ static int nvme_trans_start_stop(struct nvme_ns *ns, struct sg_io_hdr *hdr,
if (res)
return res;
}
- /* Setup the expected power state transition */
- return nvme_trans_power_state(ns, hdr, pc, pcmod, start);
+
+ return 0;
}
}

--
2.7.4
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