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qcacld-3.0: Avoid deadlock during suspend and resume

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Presently in the driver, we get the MSI interrupt to wake up from
suspend which directs the call to the both kernel and driver. In the
driver, the HIF callback target_initial_wakeup_cb registered, gets
called in interrupt context while that through the kernel get scheduled
in thread context. These two call can potentially get into a deadlock.

The scenario can be described as:
	- MSI interrupt raised
	- callback invoked from kernel -> takes spinlock on psoc->lock
	- hif callback in interrupt context -> spins on the same psoc->lock
	- deadlock

The problem arises due to the fact that both the kernel thread and the
interrupt handler are executing on the same CPU. This causes the
spinlock in the interrupt context to spin forever.

The solution to mitigate this scenario is to not take the reference
inside the hif callback pmo_core_psoc_handle_initial_wake_up. This
reference was put in place to prevent the wake up callback from getting
affected by psoc creation and deletion. But there seems no need for this
as creation and deletion of psoc happens outside the time-scope of the
wake up callback.

Change-Id: I566ab08802ba3f38e154d26599c73d718ec74bfb
CRs-Fixed: 2556497
This commit is contained in:
Sourav Mohapatra
2019-11-01 12:01:14 +05:30
committed by nshrivas
parent 2b3843e027
commit ffcaf378c7
1 changed files with 0 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
components/pmo/core/src/wlan_pmo_suspend_resume.c
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@@ -1450,7 +1450,6 @@ void pmo_core_psoc_handle_initial_wake_up(void *cb_ctx)
{
struct pmo_psoc_priv_obj *psoc_ctx;
struct wlan_objmgr_psoc *psoc = (struct wlan_objmgr_psoc *)cb_ctx;
QDF_STATUS status;
pmo_enter();
if (!psoc) {
@@ -1458,17 +1457,9 @@ void pmo_core_psoc_handle_initial_wake_up(void *cb_ctx)
goto out;
}
status = pmo_psoc_get_ref(psoc);
if (status != QDF_STATUS_SUCCESS) {
pmo_err("Failed to get psoc reference");
goto out;
}
psoc_ctx = pmo_psoc_get_priv(psoc);
pmo_core_update_wow_initial_wake_up(psoc_ctx, true);
pmo_psoc_put_ref(psoc);
out:
pmo_exit();
}