diff options
| author | Daniel Thompson <daniel.thompson@linaro.org> | 2022-04-13 16:04:07 +0100 |
|---|---|---|
| committer | Daniel Thompson <daniel.thompson@linaro.org> | 2022-04-13 17:22:53 +0100 |
| commit | 4f886ca3243fd3ede50a2064c548aa6a5ef5a65e (patch) | |
| tree | 79464ecf0c1a7593aa81d67e5c1734d9c1251b61 | |
| parent | d11936e6dfeb5eb28f5be3f5fe80de0d47b8de6a (diff) | |
kgdb: spinlock wrappers that degrade to trylock if halted for debug
kgdb (and kdb) runs in an unusual calling context and most spin locking
whilst cores are halted inside the debugger risks deadlock. kgdb is largely
successful in avoiding incorrect use of locks. However kdb has an element
of "fingers crossed and hope" regarding lock correctness. In practice this
isn't quite as awful as it sounds (users do not continually walk face first
into deadlocks) but we need to start fixing some of these problems.
The major problem with fixing them by avoiding locks altogether is that we
end up with a robust-but-feature-free debugger that can't summarize the
system state in a manner the developer at the keyboard can absorb.
Let's try to tackle this by introducing locking calls that can degrade to
trylock if we are running in the debugger. These new locking calls allow us
to provide graceful failure instead of deadlock in some cases. They are
also designed to permit dead-code elimination to keep !CONFIG_KGDB kernels
from paying the cost.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
| -rw-r--r-- | include/linux/kgdb.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index 258cdde8d356..9007037df142 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -366,4 +366,11 @@ extern void kgdb_free_init_mem(void); static inline void kgdb_panic(const char *msg) {} static inline void kgdb_free_init_mem(void) { } #endif /* ! CONFIG_KGDB */ + +#define raw_spin_lock_irqsave_dbg(lock, flags) \ + (in_dbg_master() \ + ? ({ raw_spin_trylock_irqsave(lock, flags); }) \ + : ({ raw_spin_lock_irqsave(lock, flags); 1; }) \ + ) + #endif /* _KGDB_H_ */ |