On a Thinkpad s30 (Pentium III / i440MX, Lynx3DM), rebooting with
sm712fb framebuffer driver would cause the role of brightness up/down
button to swap.
Experiments showed the FPR30 register caused this behavior. Moreover,
even if this register don't have side-effect on other systems, over-
writing it is also highly questionable, since it was originally
configurated by the motherboard manufacturer by hardwiring pull-down
resistors to indicate the type of LCD panel. We should not mess with
it.
Stop writing to the SR30 (a.k.a FPR30) register.
Signed-off-by: Yifeng Li <tomli(a)tomli.me>
Cc: stable(a)vger.kernel.org # v4.4+
---
drivers/video/fbdev/sm712fb.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c
index d05379affa32..a19655babf67 100644
--- a/drivers/video/fbdev/sm712fb.c
+++ b/drivers/video/fbdev/sm712fb.c
@@ -1145,8 +1145,8 @@ static void sm7xx_set_timing(struct smtcfb_info *sfb)
/* init SEQ register SR30 - SR75 */
for (i = 0; i < SIZE_SR30_SR75; i++)
- if ((i + 0x30) != 0x62 && (i + 0x30) != 0x6a &&
- (i + 0x30) != 0x6b)
+ if ((i + 0x30) != 0x30 && (i + 0x30) != 0x62 &&
+ (i + 0x30) != 0x6a && (i + 0x30) != 0x6b)
smtc_seqw(i + 0x30,
vgamode[j].init_sr30_sr75[i]);
--
2.20.1
On a Thinkpad s30 (Pentium III / i440MX, Lynx3DM), rebooting with
sm712fb framebuffer driver would cause a white screen of death on
the next POST, presumably the proper timings for the LCD panel was
not reprogrammed properly by the BIOS.
Experiments showed a few CRTC Scratch Registers, including CRT3D,
CRT3E and CRT3F may be used internally by BIOS as some flags. CRT3B is
a hardware testing register, we shouldn't mess with it. CRT3C has
blanking signal and line compare control, which is not needed for this
driver.
Stop writing to CR3B-CR3F (a.k.a CRT3B-CRT3F) registers. Even if these
registers don't have side-effect on other systems, writing to them is
also highly questionable.
Signed-off-by: Yifeng Li <tomli(a)tomli.me>
Cc: stable(a)vger.kernel.org # v4.4+
---
drivers/video/fbdev/sm712fb.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/video/fbdev/sm712fb.c b/drivers/video/fbdev/sm712fb.c
index 502d0de2feec..d05379affa32 100644
--- a/drivers/video/fbdev/sm712fb.c
+++ b/drivers/video/fbdev/sm712fb.c
@@ -1171,8 +1171,12 @@ static void sm7xx_set_timing(struct smtcfb_info *sfb)
smtc_crtcw(i, vgamode[j].init_cr00_cr18[i]);
/* init CRTC register CR30 - CR4D */
- for (i = 0; i < SIZE_CR30_CR4D; i++)
+ for (i = 0; i < SIZE_CR30_CR4D; i++) {
+ if ((i + 0x30) >= 0x3B && (i + 0x30) <= 0x3F)
+ /* side-effect, don't write to CR3B-CR3F */
+ continue;
smtc_crtcw(i + 0x30, vgamode[j].init_cr30_cr4d[i]);
+ }
/* init CRTC register CR90 - CRA7 */
for (i = 0; i < SIZE_CR90_CRA7; i++)
--
2.20.1
From: "Gautham R. Shenoy" <ego(a)linux.vnet.ibm.com>
In cpu_to_drc_index() in the case when FW_FEATURE_DRC_INFO is absent,
we currently use of_read_property() to obtain the pointer to the array
corresponding to the property "ibm,drc-indexes". The elements of this
array are of type __be32, but are accessed without any conversion to
the OS-endianness, which is buggy on a Little Endian OS.
Fix this by using of_property_read_u32_index() accessor function to
safely read the elements of the array.
Fixes: commit e83636ac3334 ("pseries/drc-info: Search DRC properties for CPU indexes")
Cc: <stable(a)vger.kernel.org> #v4.16+
Reported-by: Pavithra R. Prakash <pavrampu(a)in.ibm.com>
Signed-off-by: Gautham R. Shenoy <ego(a)linux.vnet.ibm.com>
---
arch/powerpc/platforms/pseries/pseries_energy.c | 27 ++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/pseries_energy.c b/arch/powerpc/platforms/pseries/pseries_energy.c
index 6ed2212..1c4d1ba 100644
--- a/arch/powerpc/platforms/pseries/pseries_energy.c
+++ b/arch/powerpc/platforms/pseries/pseries_energy.c
@@ -77,18 +77,27 @@ static u32 cpu_to_drc_index(int cpu)
ret = drc.drc_index_start + (thread_index * drc.sequential_inc);
} else {
- const __be32 *indexes;
-
- indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
- if (indexes == NULL)
- goto err_of_node_put;
+ u32 nr_drc_indexes, thread_drc_index;
/*
- * The first element indexes[0] is the number of drc_indexes
- * returned in the list. Hence thread_index+1 will get the
- * drc_index corresponding to core number thread_index.
+ * The first element of ibm,drc-indexes array is the
+ * number of drc_indexes returned in the list. Hence
+ * thread_index+1 will get the drc_index corresponding
+ * to core number thread_index.
*/
- ret = indexes[thread_index + 1];
+ rc = of_property_read_u32_index(dn, "ibm,drc-indexes",
+ 0, &nr_drc_indexes);
+ if (rc)
+ goto err_of_node_put;
+
+ WARN_ON(thread_index > nr_drc_indexes);
+ rc = of_property_read_u32_index(dn, "ibm,drc-indexes",
+ thread_index + 1,
+ &thread_drc_index);
+ if (rc)
+ goto err_of_node_put;
+
+ ret = thread_drc_index;
}
rc = 0;
--
1.9.4
c2856ae2f315d ("blk-mq: quiesce queue before freeing queue") has
already fixed this race, however the implied synchronize_rcu()
in blk_mq_quiesce_queue() can slow down LUN probe a lot, so caused
performance regression.
Then 1311326cf4755c7 ("blk-mq: avoid to synchronize rcu inside blk_cleanup_queue()")
tried to quiesce queue for avoiding unnecessary synchronize_rcu()
only when queue initialization is done, because it is usual to see
lots of inexistent LUNs which need to be probed.
However, turns out it isn't safe to quiesce queue only when queue
initialization is done. Because when one SCSI command is completed,
the user of sending command can be waken up immediately, then the
scsi device may be removed, meantime the run queue in scsi_end_request()
is still in-progress, so kernel panic can be caused.
In Red Hat QE lab, there are several reports about this kind of kernel
panic triggered during kernel booting.
This patch tries to address the issue by grabing one queue usage
counter during freeing one request and the following run queue.
Fixes: 1311326cf4755c7 ("blk-mq: avoid to synchronize rcu inside blk_cleanup_queue()")
Cc: Andrew Jones <drjones(a)redhat.com>
Cc: Bart Van Assche <bart.vanassche(a)wdc.com>
Cc: linux-scsi(a)vger.kernel.org
Cc: Martin K. Petersen <martin.petersen(a)oracle.com>
Cc: Christoph Hellwig <hch(a)lst.de>
Cc: James E.J. Bottomley <jejb(a)linux.vnet.ibm.com>
Cc: stable <stable(a)vger.kernel.org>
Cc: jianchao.wang <jianchao.w.wang(a)oracle.com>
Signed-off-by: Ming Lei <ming.lei(a)redhat.com>
---
block/blk-core.c | 5 ++---
drivers/scsi/scsi_lib.c | 8 ++++++++
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index ce12515f9b9b..deb56932f8c4 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -798,9 +798,8 @@ void blk_cleanup_queue(struct request_queue *q)
* dispatch may still be in-progress since we dispatch requests
* from more than one contexts.
*
- * No need to quiesce queue if it isn't initialized yet since
- * blk_freeze_queue() should be enough for cases of passthrough
- * request.
+ * We rely on driver to deal with the race in case that queue
+ * initialization isn't done.
*/
if (q->mq_ops && blk_queue_init_done(q))
blk_mq_quiesce_queue(q);
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index c7fccbb8f554..fa6e0c3b3aa6 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -697,6 +697,12 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
*/
scsi_mq_uninit_cmd(cmd);
+ /*
+ * queue is still alive, so grab the ref for preventing it
+ * from being cleaned up during running queue.
+ */
+ percpu_ref_get(&q->q_usage_counter);
+
__blk_mq_end_request(req, error);
if (scsi_target(sdev)->single_lun ||
@@ -704,6 +710,8 @@ static bool scsi_end_request(struct request *req, blk_status_t error,
kblockd_schedule_work(&sdev->requeue_work);
else
blk_mq_run_hw_queues(q, true);
+
+ percpu_ref_put(&q->q_usage_counter);
} else {
unsigned long flags;
--
2.9.5