Hi Tingwei
On Tue, 18 Aug 2020 at 12:11, Tingwei Zhang tingwei@codeaurora.org wrote:
Deadlock as below is triggered by one CPU holds drvdata->spinlock and calls cti_enable_hw(). Smp_call_function_single() is called in cti_enable_hw() and tries to let another CPU write CTI registers. That CPU is trying to get drvdata->spinlock in cti_cpu_pm_notify() and doesn't response to IPI from smp_call_function_single().
[ 988.335937] CPU: 6 PID: 10258 Comm: sh Tainted: G W L 5.8.0-rc6-mainline-16783-gc38daa79b26b-dirty #1 [ 988.346364] Hardware name: Thundercomm Dragonboard 845c (DT) [ 988.352073] pstate: 20400005 (nzCv daif +PAN -UAO BTYPE=--) [ 988.357689] pc : smp_call_function_single+0x158/0x1b8 [ 988.362782] lr : smp_call_function_single+0x124/0x1b8 ... [ 988.451638] Call trace: [ 988.454119] smp_call_function_single+0x158/0x1b8 [ 988.458866] cti_enable+0xb4/0xf8 [coresight_cti] [ 988.463618] coresight_control_assoc_ectdev+0x6c/0x128 [coresight] [ 988.469855] coresight_enable+0x1f0/0x364 [coresight] [ 988.474957] enable_source_store+0x5c/0x9c [coresight] [ 988.480140] dev_attr_store+0x14/0x28 [ 988.483839] sysfs_kf_write+0x38/0x4c [ 988.487532] kernfs_fop_write+0x1c0/0x2b0 [ 988.491585] vfs_write+0xfc/0x300 [ 988.494931] ksys_write+0x78/0xe0 [ 988.498283] __arm64_sys_write+0x18/0x20 [ 988.502240] el0_svc_common+0x98/0x160 [ 988.506024] do_el0_svc+0x78/0x80 [ 988.509377] el0_sync_handler+0xd4/0x270 [ 988.513337] el0_sync+0x164/0x180
This change write CTI registers directly in cti_enable_hw(). Config->hw_powered has been checked to be true with spinlock holded. CTI is powered and can be programmed until spinlock is released.
Agreed.
Reviewed-by Mike Leach mike.leach@linaro.org
Fixes: 6a0953ce7de9 ("coresight: cti: Add CPU idle pm notifer to CTI devices") Signed-off-by: Tingwei Zhang tingwei@codeaurora.org
drivers/hwtracing/coresight/coresight-cti.c | 17 +---------------- 1 file changed, 1 insertion(+), 16 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-cti.c b/drivers/hwtracing/coresight/coresight-cti.c index 3ccc703dc940..869569eb8c7f 100644 --- a/drivers/hwtracing/coresight/coresight-cti.c +++ b/drivers/hwtracing/coresight/coresight-cti.c @@ -86,13 +86,6 @@ void cti_write_all_hw_regs(struct cti_drvdata *drvdata) CS_LOCK(drvdata->base); }
-static void cti_enable_hw_smp_call(void *info) -{
struct cti_drvdata *drvdata = info;cti_write_all_hw_regs(drvdata);-}
/* write regs to hardware and enable */ static int cti_enable_hw(struct cti_drvdata *drvdata) { @@ -112,15 +105,7 @@ static int cti_enable_hw(struct cti_drvdata *drvdata) if (rc) goto cti_err_not_enabled;
if (drvdata->ctidev.cpu >= 0) {rc = smp_call_function_single(drvdata->ctidev.cpu,cti_enable_hw_smp_call,drvdata, 1);if (rc)goto cti_err_not_enabled;} else {cti_write_all_hw_regs(drvdata);}
cti_write_all_hw_regs(drvdata); config->hw_enabled = true; atomic_inc(&drvdata->config.enable_req_count);-- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
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