CVE-2023-52791

In the Linux kernel, the following vulnerability has been resolved:

i2c: core: Run atomic i2c xfer when !preemptible

Since bae1d3a05a8b, i2c transfers are non-atomic if preemption is disabled. However, non-atomic i2c transfers require preemption (e.g. in waitforcompletion() while waiting for the DMA).

panic() calls preemptdisablenotrace() before calling emergency_restart(). Therefore, if an i2c device is used for the restart, the xfer should be atomic. This avoids warnings like:

[ 12.667612] WARNING: CPU: 1 PID: 1 at kernel/rcu/treeplugin.h:318 rcunotecontextswitch+0x33c/0x6b0 [ 12.676926] Voluntary context switch within RCU read-side critical section! ... [ 12.742376] scheduletimeout from waitforcompletiontimeout+0x90/0x114 [ 12.749179] waitforcompletiontimeout from tegrai2cwaitcompletion+0x40/0x70 ... [ 12.994527] atomicnotifiercallchain from machinerestart+0x34/0x58 [ 13.001050] machine_restart from panic+0x2a8/0x32c

Use !preemptible() instead, which is basically the same check as pre-v5.2.