linux-toradex.git/drivers/devfreq/devfreq.c, branch v6.13-rc1

PM / devfreq: Synchronize devfreq_monitor_[start/stop]

2023-12-18T22:58:27+00:00

There is a chance if a frequent switch of the governor
done in a loop result in timer list corruption where
timer cancel being done from two place one from
cancel_delayed_work_sync() and followed by expire_timers()
can be seen from the traces[1].

while true
do
        echo "simple_ondemand" > /sys/class/devfreq/1d84000.ufshc/governor
        echo "performance" > /sys/class/devfreq/1d84000.ufshc/governor
done

It looks to be issue with devfreq driver where
device_monitor_[start/stop] need to synchronized so that
delayed work should get corrupted while it is either
being queued or running or being cancelled.

Let's use polling flag and devfreq lock to synchronize the
queueing the timer instance twice and work data being
corrupted.

[1]
...
..
-0    [003]   9436.209662:  timer_cancel   timer=0xffffff80444f0428
-0    [003]   9436.209664:  timer_expire_entry   timer=0xffffff80444f0428  now=0x10022da1c  function=__typeid__ZTSFvP10timer_listE_global_addr  baseclk=0x10022da1c
-0    [003]   9436.209718:  timer_expire_exit   timer=0xffffff80444f0428
kworker/u16:6-14217    [003]   9436.209863:  timer_start   timer=0xffffff80444f0428  function=__typeid__ZTSFvP10timer_listE_global_addr  expires=0x10022da2b  now=0x10022da1c  flags=182452227
vendor.xxxyyy.ha-1593    [004]   9436.209888:  timer_cancel   timer=0xffffff80444f0428
vendor.xxxyyy.ha-1593    [004]   9436.216390:  timer_init   timer=0xffffff80444f0428
vendor.xxxyyy.ha-1593    [004]   9436.216392:  timer_start   timer=0xffffff80444f0428  function=__typeid__ZTSFvP10timer_listE_global_addr  expires=0x10022da2c  now=0x10022da1d  flags=186646532
vendor.xxxyyy.ha-1593    [005]   9436.220992:  timer_cancel   timer=0xffffff80444f0428
xxxyyyTraceManag-7795    [004]   9436.261641:  timer_cancel   timer=0xffffff80444f0428

[2]

 9436.261653][    C4] Unable to handle kernel paging request at virtual address dead00000000012a
[ 9436.261664][    C4] Mem abort info:
[ 9436.261666][    C4]   ESR = 0x96000044
[ 9436.261669][    C4]   EC = 0x25: DABT (current EL), IL = 32 bits
[ 9436.261671][    C4]   SET = 0, FnV = 0
[ 9436.261673][    C4]   EA = 0, S1PTW = 0
[ 9436.261675][    C4] Data abort info:
[ 9436.261677][    C4]   ISV = 0, ISS = 0x00000044
[ 9436.261680][    C4]   CM = 0, WnR = 1
[ 9436.261682][    C4] [dead00000000012a] address between user and kernel address ranges
[ 9436.261685][    C4] Internal error: Oops: 96000044 [#1] PREEMPT SMP
[ 9436.261701][    C4] Skip md ftrace buffer dump for: 0x3a982d0
...

[ 9436.262138][    C4] CPU: 4 PID: 7795 Comm: TraceManag Tainted: G S      W  O      5.10.149-android12-9-o-g17f915d29d0c #1
[ 9436.262141][    C4] Hardware name: Qualcomm Technologies, Inc.  (DT)
[ 9436.262144][    C4] pstate: 22400085 (nzCv daIf +PAN -UAO +TCO BTYPE=--)
[ 9436.262161][    C4] pc : expire_timers+0x9c/0x438
[ 9436.262164][    C4] lr : expire_timers+0x2a4/0x438
[ 9436.262168][    C4] sp : ffffffc010023dd0
[ 9436.262171][    C4] x29: ffffffc010023df0 x28: ffffffd0636fdc18
[ 9436.262178][    C4] x27: ffffffd063569dd0 x26: ffffffd063536008
[ 9436.262182][    C4] x25: 0000000000000001 x24: ffffff88f7c69280
[ 9436.262185][    C4] x23: 00000000000000e0 x22: dead000000000122
[ 9436.262188][    C4] x21: 000000010022da29 x20: ffffff8af72b4e80
[ 9436.262191][    C4] x19: ffffffc010023e50 x18: ffffffc010025038
[ 9436.262195][    C4] x17: 0000000000000240 x16: 0000000000000201
[ 9436.262199][    C4] x15: ffffffffffffffff x14: ffffff889f3c3100
[ 9436.262203][    C4] x13: ffffff889f3c3100 x12: 00000000049f56b8
[ 9436.262207][    C4] x11: 00000000049f56b8 x10: 00000000ffffffff
[ 9436.262212][    C4] x9 : ffffffc010023e50 x8 : dead000000000122
[ 9436.262216][    C4] x7 : ffffffffffffffff x6 : ffffffc0100239d8
[ 9436.262220][    C4] x5 : 0000000000000000 x4 : 0000000000000101
[ 9436.262223][    C4] x3 : 0000000000000080 x2 : ffffff889edc155c
[ 9436.262227][    C4] x1 : ffffff8001005200 x0 : ffffff80444f0428
[ 9436.262232][    C4] Call trace:
[ 9436.262236][    C4]  expire_timers+0x9c/0x438
[ 9436.262240][    C4]  __run_timers+0x1f0/0x330
[ 9436.262245][    C4]  run_timer_softirq+0x28/0x58
[ 9436.262255][    C4]  efi_header_end+0x168/0x5ec
[ 9436.262265][    C4]  __irq_exit_rcu+0x108/0x124
[ 9436.262274][    C4]  __handle_domain_irq+0x118/0x1e4
[ 9436.262282][    C4]  gic_handle_irq.30369+0x6c/0x2bc
[ 9436.262286][    C4]  el0_irq_naked+0x60/0x6c

Link: https://lore.kernel.org/all/1700860318-4025-1-git-send-email-quic_mojha@quicinc.com/
Reported-by: Joyyoung Huang 
Acked-by: MyungJoo Ham 
Signed-off-by: Mukesh Ojha 
Signed-off-by: Chanwoo Choi

PM / devfreq: Convert to use sysfs_emit_at() API

2023-11-13T01:48:49+00:00

Follow the advice of the Documentation/filesystems/sysfs.rst and show()
should only use sysfs_emit() or sysfs_emit_at() when formatting the
value to be returned to user space.

Link: https://lore.kernel.org/all/20231024183016.14648-3-ansuelsmth@gmail.com/
Signed-off-by: Christian Marangi 
Signed-off-by: Chanwoo Choi

PM / devfreq: Fix buffer overflow in trans_stat_show

2023-11-13T01:48:49+00:00

Fix buffer overflow in trans_stat_show().

Convert simple snprintf to the more secure scnprintf with size of
PAGE_SIZE.

Add condition checking if we are exceeding PAGE_SIZE and exit early from
loop. Also add at the end a warning that we exceeded PAGE_SIZE and that
stats is disabled.

Return -EFBIG in the case where we don't have enough space to write the
full transition table.

Also document in the ABI that this function can return -EFBIG error.

Link: https://lore.kernel.org/all/20231024183016.14648-2-ansuelsmth@gmail.com/
Cc: stable@vger.kernel.org
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218041
Fixes: e552bbaf5b98 ("PM / devfreq: Add sysfs node for representing frequency transition information.")
Signed-off-by: Christian Marangi 
Signed-off-by: Chanwoo Choi

PM / devfreq: Switch to dev_pm_opp_find_freq_{ceil/floor}_indexed() APIs

2023-10-08T22:28:50+00:00

Some devfreq consumers like UFS driver need to work with multiple clocks
through the OPP framework. For this reason, OPP framework exposes the
_indexed() APIs for finding the floor/ceil of the supplied frequency of
the indexed clock. So let's use them in the devfreq driver.

Currently, the clock index of 0 is used which works fine for multiple as
well as single clock.

Link: https://lore.kernel.org/all/20231003111232.42663-3-manivannan.sadhasivam@linaro.org/
Acked-by: Chanwoo Choi 
Signed-off-by: Manivannan Sadhasivam 
Signed-off-by: Chanwoo Choi

PM / devfreq: Fix leak in devfreq_dev_release()

2023-08-10T13:48:16+00:00

srcu_init_notifier_head() allocates resources that need to be released
with a srcu_cleanup_notifier_head() call.

Reported by kmemleak.

Fixes: 0fe3a66410a3 ("PM / devfreq: Add new DEVFREQ_TRANSITION_NOTIFIER notifier")
Cc: 
Signed-off-by: Boris Brezillon 
Reviewed-by: Dhruva Gole 
Signed-off-by: Chanwoo Choi

PM / devfreq: Reword the kernel-doc comment for devfreq_monitor_start() API

2023-07-23T20:24:36+00:00

Current kernel-doc comment doesn't specify the default timer used for the
load monitoring. Also, it uses the term "default delayed work" which could
be misunderstood as "default delayer timer". So reword the comment to
clearly specify the default timer and also reword the last sentence to make
it more understandable.

Signed-off-by: Manivannan Sadhasivam 
Signed-off-by: Chanwoo Choi

driver core: class: remove module * from class_create()

2023-03-17T14:16:33+00:00

The module pointer in class_create() never actually did anything, and it
shouldn't have been requred to be set as a parameter even if it did
something.  So just remove it and fix up all callers of the function in
the kernel tree at the same time.

Cc: "Rafael J. Wysocki" 
Acked-by: Benjamin Tissoires 
Link: https://lore.kernel.org/r/20230313181843.1207845-4-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman

PM / devfreq: Use device_match_of_node()

2022-12-02T23:04:40+00:00

Replace the open-code with device_match_of_node().

Signed-off-by: ye xingchen 
Signed-off-by: Chanwoo Choi

PM/devfreq: governor: Add a private governor_data for governor

2022-11-20T11:49:51+00:00

The member void *data in the structure devfreq can be overwrite
by governor_userspace. For example:
1. The device driver assigned the devfreq governor to simple_ondemand
by the function devfreq_add_device() and init the devfreq member
void *data to a pointer of a static structure devfreq_simple_ondemand_data
by the function devfreq_add_device().
2. The user changed the devfreq governor to userspace by the command
"echo userspace > /sys/class/devfreq/.../governor".
3. The governor userspace alloced a dynamic memory for the struct
userspace_data and assigend the member void *data of devfreq to
this memory by the function userspace_init().
4. The user changed the devfreq governor back to simple_ondemand
by the command "echo simple_ondemand > /sys/class/devfreq/.../governor".
5. The governor userspace exited and assigned the member void *data
in the structure devfreq to NULL by the function userspace_exit().
6. The governor simple_ondemand fetched the static information of
devfreq_simple_ondemand_data in the function
devfreq_simple_ondemand_func() but the member void *data of devfreq was
assigned to NULL by the function userspace_exit().
7. The information of upthreshold and downdifferential is lost
and the governor simple_ondemand can't work correctly.

The member void *data in the structure devfreq is designed for
a static pointer used in a governor and inited by the function
devfreq_add_device(). This patch add an element named governor_data
in the devfreq structure which can be used by a governor(E.g userspace)
who want to assign a private data to do some private things.

Fixes: ce26c5bb9569 ("PM / devfreq: Add basic governors")
Cc: stable@vger.kernel.org # 5.10+
Reviewed-by: Chanwoo Choi 
Acked-by: MyungJoo Ham 
Signed-off-by: Kant Fan 
Signed-off-by: Chanwoo Choi

PM / devfreq: shut up kernel-doc warnings

2022-07-15T02:40:08+00:00

There are 4 warnings there:
	drivers/devfreq/devfreq.c:707: warning: Function parameter or member 'val' not described in 'qos_min_notifier_call'
	drivers/devfreq/devfreq.c:707: warning: Function parameter or member 'ptr' not described in 'qos_min_notifier_call'
	drivers/devfreq/devfreq.c:717: warning: Function parameter or member 'val' not described in 'qos_max_notifier_call'
	drivers/devfreq/devfreq.c:717: warning: Function parameter or member 'ptr' not described in 'qos_max_notifier_call'

It turns that neither val nor ptr are actually used on those
function, so document as such.

Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Chanwoo Choi