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bpf: Report rqspinlock deadlocks/timeout to BPF stderr 

Begin reporting rqspinlock deadlocks and timeout to BPF program's
stderr.

Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-9-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
pull/1309/head
Kumar Kartikeya Dwivedi 2025-07-03 13:48:14 -07:00 committed by Alexei Starovoitov
parent e8d0133022
commit ecec5b5743
1 changed files with 23 additions and 0 deletions
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23
kernel/bpf/rqspinlock.c
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@ -666,6 +666,27 @@ EXPORT_SYMBOL_GPL(resilient_queued_spin_lock_slowpath);
__bpf_kfunc_start_defs(); __bpf_kfunc_start_defs();
static void bpf_prog_report_rqspinlock_violation(const char *str, void *lock, bool irqsave)
{
struct rqspinlock_held *rqh = this_cpu_ptr(&rqspinlock_held_locks);
struct bpf_stream_stage ss;
struct bpf_prog *prog;
prog = bpf_prog_find_from_stack();
if (!prog)
return;
bpf_stream_stage(ss, prog, BPF_STDERR, ({
bpf_stream_printk(ss, "ERROR: %s for bpf_res_spin_lock%s\n", str, irqsave ? "_irqsave" : "");
bpf_stream_printk(ss, "Attempted lock = 0x%px\n", lock);
bpf_stream_printk(ss, "Total held locks = %d\n", rqh->cnt);
for (int i = 0; i < min(RES_NR_HELD, rqh->cnt); i++)
bpf_stream_printk(ss, "Held lock[%2d] = 0x%px\n", i, rqh->locks[i]);
bpf_stream_dump_stack(ss);
}));
}
#define REPORT_STR(ret) ({ (ret) == -ETIMEDOUT ? "Timeout detected" : "AA or ABBA deadlock detected"; })
__bpf_kfunc int bpf_res_spin_lock(struct bpf_res_spin_lock *lock) __bpf_kfunc int bpf_res_spin_lock(struct bpf_res_spin_lock *lock)
{ {
int ret; int ret;
@ -676,6 +697,7 @@ __bpf_kfunc int bpf_res_spin_lock(struct bpf_res_spin_lock *lock)
preempt_disable(); preempt_disable();
ret = res_spin_lock((rqspinlock_t *)lock); ret = res_spin_lock((rqspinlock_t *)lock);
if (unlikely(ret)) { if (unlikely(ret)) {
bpf_prog_report_rqspinlock_violation(REPORT_STR(ret), lock, false);
preempt_enable(); preempt_enable();
return ret; return ret;
} }
@ -698,6 +720,7 @@ __bpf_kfunc int bpf_res_spin_lock_irqsave(struct bpf_res_spin_lock *lock, unsign
local_irq_save(flags); local_irq_save(flags);
ret = res_spin_lock((rqspinlock_t *)lock); ret = res_spin_lock((rqspinlock_t *)lock);
if (unlikely(ret)) { if (unlikely(ret)) {
bpf_prog_report_rqspinlock_violation(REPORT_STR(ret), lock, true);
local_irq_restore(flags); local_irq_restore(flags);
preempt_enable(); preempt_enable();
return ret; return ret;