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| author | Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> | 2019-03-04 20:42:19 +0100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2019-05-02 18:54:57 +0200 |
| commit | de269129a48a2d590ba1d20c719e19d86e3ddb3f (patch) | |
| tree | f24b4a3afde2d90ce614a347129acf6324315a1a /arch/powerpc/kernel/time.c | |
| parent | powerpc/xmon: add read-only mode (diff) | |
| download | linux-de269129a48a2d590ba1d20c719e19d86e3ddb3f.tar.xz linux-de269129a48a2d590ba1d20c719e19d86e3ddb3f.zip | |
powerpc/hmi: Fix kernel hang when TB is in error state.
On TOD/TB errors timebase register stops/freezes until HMI error recovery
gets TOD/TB back into running state. On successful recovery, TB starts
running again and udelay() that relies on TB value continues to function
properly. But in case when HMI fails to recover from TOD/TB errors, the
TB register stay freezed. With TB not running the __delay() function
keeps looping and never return. If __delay() is called while in panic
path then system hangs and never reboots after panic.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/time.c')
| -rw-r--r-- | arch/powerpc/kernel/time.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 6ef32472ee1d..325d60633dfa 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -150,6 +150,8 @@ EXPORT_SYMBOL_GPL(ppc_proc_freq); unsigned long ppc_tb_freq; EXPORT_SYMBOL_GPL(ppc_tb_freq); +bool tb_invalid; + #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE /* * Factor for converting from cputime_t (timebase ticks) to @@ -459,6 +461,13 @@ void __delay(unsigned long loops) diff += 1000000000; spin_cpu_relax(); } while (diff < loops); + } else if (tb_invalid) { + /* + * TB is in error state and isn't ticking anymore. + * HMI handler was unable to recover from TB error. + * Return immediately, so that kernel won't get stuck here. + */ + spin_cpu_relax(); } else { start = get_tbl(); while (get_tbl() - start < loops) |