diff options
author | Hans de Goede <hdegoede@redhat.com> | 2021-02-17 11:24:59 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-03-24 08:26:29 +0100 |
commit | 3641762c1c9c7cfd84a7061a0a73054f09b412e3 (patch) | |
tree | 47b84528e647fb16870880ce7546eec799d683d0 | |
parent | 25651f2df7833c5554f51652007862a405aac830 (diff) |
misc: lis3lv02d: Fix false-positive WARN on various HP models
Before this commit lis3lv02d_get_pwron_wait() had a WARN_ONCE() to catch
a potential divide by 0. WARN macros should only be used to catch internal
kernel bugs and that is not the case here. We have been receiving a lot of
bug reports about kernel backtraces caused by this WARN.
The div value being checked comes from the lis3->odrs[] array. Which
is sized to be a power-of-2 matching the number of bits in lis3->odr_mask.
The only lis3 model where this array is not entirely filled with non zero
values. IOW the only model where we can hit the div == 0 check is the
3dc ("8 bits 3DC sensor") model:
int lis3_3dc_rates[16] = {0, 1, 10, 25, 50, 100, 200, 400, 1600, 5000};
Note the 0 value at index 0, according to the datasheet an odr index of 0
means "Power-down mode". HP typically uses a lis3 accelerometer for HDD
fall protection. What I believe is happening here is that on newer
HP devices, which only contain a SDD, the BIOS is leaving the lis3 device
powered-down since it is not used for HDD fall protection.
Note that the lis3_3dc_rates array initializer only specifies 10 values,
which matches the datasheet. So it also contains 6 zero values at the end.
Replace the WARN with a normal check, which treats an odr index of 0
as power-down and uses a normal dev_err() to report the error in case
odr index point past the initialized part of the array.
Fixes: 1510dd5954be ("lis3lv02d: avoid divide by zero due to unchecked")
Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=785814
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1817027
BugLink: https://bugs.centos.org/view.php?id=10720
Link: https://lore.kernel.org/r/20210217102501.31758-1-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/misc/lis3lv02d/lis3lv02d.c | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/drivers/misc/lis3lv02d/lis3lv02d.c b/drivers/misc/lis3lv02d/lis3lv02d.c index dd65cedf3b12..9d14bf444481 100644 --- a/drivers/misc/lis3lv02d/lis3lv02d.c +++ b/drivers/misc/lis3lv02d/lis3lv02d.c @@ -208,7 +208,7 @@ static int lis3_3dc_rates[16] = {0, 1, 10, 25, 50, 100, 200, 400, 1600, 5000}; static int lis3_3dlh_rates[4] = {50, 100, 400, 1000}; /* ODR is Output Data Rate */ -static int lis3lv02d_get_odr(struct lis3lv02d *lis3) +static int lis3lv02d_get_odr_index(struct lis3lv02d *lis3) { u8 ctrl; int shift; @@ -216,15 +216,23 @@ static int lis3lv02d_get_odr(struct lis3lv02d *lis3) lis3->read(lis3, CTRL_REG1, &ctrl); ctrl &= lis3->odr_mask; shift = ffs(lis3->odr_mask) - 1; - return lis3->odrs[(ctrl >> shift)]; + return (ctrl >> shift); } static int lis3lv02d_get_pwron_wait(struct lis3lv02d *lis3) { - int div = lis3lv02d_get_odr(lis3); + int odr_idx = lis3lv02d_get_odr_index(lis3); + int div = lis3->odrs[odr_idx]; - if (WARN_ONCE(div == 0, "device returned spurious data")) + if (div == 0) { + if (odr_idx == 0) { + /* Power-down mode, not sampling no need to sleep */ + return 0; + } + + dev_err(&lis3->pdev->dev, "Error unknown odrs-index: %d\n", odr_idx); return -ENXIO; + } /* LIS3 power on delay is quite long */ msleep(lis3->pwron_delay / div); @@ -816,9 +824,12 @@ static ssize_t lis3lv02d_rate_show(struct device *dev, struct device_attribute *attr, char *buf) { struct lis3lv02d *lis3 = dev_get_drvdata(dev); + int odr_idx; lis3lv02d_sysfs_poweron(lis3); - return sprintf(buf, "%d\n", lis3lv02d_get_odr(lis3)); + + odr_idx = lis3lv02d_get_odr_index(lis3); + return sprintf(buf, "%d\n", lis3->odrs[odr_idx]); } static ssize_t lis3lv02d_rate_set(struct device *dev, |