git: 2e850b832f5d - main - acpi_battery: avoid divide-by-zero when no devices have capacity info

[Ed Maste]

The branch main has been updated by emaste:

URL: 
https://cgit.FreeBSD.org/src/commit/?id=2e850b832f5d2adb9b230d191277d67c00caaab9

commit 2e850b832f5d2adb9b230d191277d67c00caaab9
Author:     Josef 'Jeff' Sipek <jef...@josefsipek.net>
AuthorDate: 2024-04-16 23:01:28 +0000
Commit:     Ed Maste <ema...@freebsd.org>
CommitDate: 2024-04-16 23:39:45 +0000

    acpi_battery: avoid divide-by-zero when no devices have capacity info
    
    On laptops with builtin batteries, disconnecting the battery may show up
    as a battery without any capacity information. (The theory is that one
    is disconnecting the cells but the electronics identifying the battery
    are still connected.) As a result, the loop over all batteries in
    acpi_battery_get_battinfo results in total_lfcap == 0.
    
    So, just check that total_lfcap is non-zero to avoid a division by zero
    (triggerable by sysctl hw.acpi.battery).
    
    Reported by:    Stefano Marinelli
    Tested by:      Stefano Marinelli
    Reviewed by:    emaste
    Differential Revision: https://reviews.freebsd.org/D44818
---
 sys/dev/acpica/acpi_battery.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/sys/dev/acpica/acpi_battery.c b/sys/dev/acpica/acpi_battery.c
index 7455c6afc6a6..cfd8261d5eab 100644
--- a/sys/dev/acpica/acpi_battery.c
+++ b/sys/dev/acpica/acpi_battery.c
@@ -266,7 +266,14 @@ acpi_battery_get_battinfo(device_t dev, struct 
acpi_battinfo *battinfo)
      */
     if (valid_units > 0) {
        if (dev == NULL) {
-           battinfo->cap = (total_cap * 100) / total_lfcap;
+           /*
+            * Avoid division by zero if none of the batteries had valid
+            * capacity info.
+            */
+           if (total_lfcap > 0)
+               battinfo->cap = (total_cap * 100) / total_lfcap;
+           else
+               battinfo->cap = 0;
            battinfo->min = total_min;
            battinfo->state = batt_stat;
            battinfo->rate = valid_rate;