Re: [PATCH v2] bus: mhi: core: Check state before processing power_down
From: Manivannan Sadhasivam
Date: Wed Feb 24 2021 - 04:56:24 EST
On Wed, Feb 17, 2021 at 09:43:31AM -0700, Jeffrey Hugo wrote:
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We cannot process a power_down if the power state is DISABLED. There is
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no valid mhi_ctxt in that case, so attepting to process the power_down
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will likely result in a null pointer dereference. If the power state is
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DISABLED, there is nothing to do anyways, so just bail early.
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Signed-off-by: Jeffrey Hugo <jhugo@xxxxxxxxxxxxxx>
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---
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v2: Fix subject and tweak the locking to avoid needless lock/unlock/relock
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drivers/bus/mhi/core/pm.c | 9 ++++++++-
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1 file changed, 8 insertions(+), 1 deletion(-)
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diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
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index 56ba3ab..47f6621 100644
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--- a/drivers/bus/mhi/core/pm.c
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+++ b/drivers/bus/mhi/core/pm.c
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@@ -1144,6 +1144,7 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
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mhi_deinit_dev_ctxt(mhi_cntrl);
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error_dev_ctxt:
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+ mhi_cntrl->pm_state = MHI_PM_DISABLE;
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mutex_unlock(&mhi_cntrl->pm_mutex);
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return ret;
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@@ -1155,11 +1156,17 @@ void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
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enum mhi_pm_state cur_state, transition_state;
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struct device *dev = &mhi_cntrl->mhi_dev->dev;
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+ mutex_lock(&mhi_cntrl->pm_mutex);
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+ cur_state = mhi_cntrl->pm_state;
As I said in my previous review, you should use pm_lock for reading the
pm_state.
Thanks,
Mani
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+ if (cur_state == MHI_PM_DISABLE) {
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+ mutex_unlock(&mhi_cntrl->pm_mutex);
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+ return; /* Already powered down */
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+ }
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+
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/* If it's not a graceful shutdown, force MHI to linkdown state */
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transition_state = (graceful) ? MHI_PM_SHUTDOWN_PROCESS :
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MHI_PM_LD_ERR_FATAL_DETECT;
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- mutex_lock(&mhi_cntrl->pm_mutex);
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write_lock_irq(&mhi_cntrl->pm_lock);
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cur_state = mhi_tryset_pm_state(mhi_cntrl, transition_state);
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if (cur_state != transition_state) {
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--
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