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coresight: cti: Write regsiters directly in cti_enable_hw()

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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.

Fixes: 6a0953ce7d ("coresight: cti: Add CPU idle pm notifer to CTI devices")
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
[Re-ordered variable declaration]
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200916191737.4001561-10-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tingwei Zhang 2020-09-16 13:17:30 -06:00 committed by Greg Kroah-Hartman
parent 4020fc8d46
commit 984f37efa3
1 changed files with 5 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
drivers/hwtracing/coresight/coresight-cti.c
View File

@ -86,22 +86,16 @@ 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)
{
struct cti_config *config = &drvdata->config;
struct device *dev = &drvdata->csdev->dev;
unsigned long flags;
int rc = 0;
pm_runtime_get_sync(dev->parent);
spin_lock(&drvdata->spinlock);
spin_lock_irqsave(&drvdata->spinlock, flags);
/* no need to do anything if enabled or unpowered*/
if (config->hw_enabled || !config->hw_powered)
@ -112,19 +106,11 @@ 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);
spin_unlock(&drvdata->spinlock);
spin_unlock_irqrestore(&drvdata->spinlock, flags);
return rc;
cti_state_unchanged:
@ -132,7 +118,7 @@ static int cti_enable_hw(struct cti_drvdata *drvdata)
/* cannot enable due to error */
cti_err_not_enabled:
spin_unlock(&drvdata->spinlock);
spin_unlock_irqrestore(&drvdata->spinlock, flags);
pm_runtime_put(dev->parent);
return rc;
}