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bus: mhi: ep: Change state_lock to mutex

Browse source 
state_lock, the spinlock type is meant to protect race against concurrent
MHI state transitions. In mhi_ep_set_m0_state(), while the state_lock is
being held, the channels are resumed in mhi_ep_resume_channels() if the
previous state was M3. This causes sleeping in atomic bug, since
mhi_ep_resume_channels() use mutex internally.

Since the state_lock is supposed to be held throughout the state change,
it is not ideal to drop the lock before calling mhi_ep_resume_channels().
So to fix this issue, let's change the type of state_lock to mutex. This
would also allow holding the lock throughout all state transitions thereby
avoiding any potential race.

Cc: <stable@vger.kernel.org> # 5.19
Fixes: e4b7b5f0f3 ("bus: mhi: ep: Add support for suspending and resuming channels")
Reported-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
This commit is contained in:
Manivannan Sadhasivam 2023-01-23 12:59:45 +05:30
parent 8a1c24bb90
commit 1ddc761829
3 changed files with 31 additions and 23 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
drivers/bus/mhi/ep/main.c
View file

@ -1001,11 +1001,11 @@ static void mhi_ep_reset_worker(struct work_struct *work)
mhi_ep_power_down(mhi_cntrl);
spin_lock_bh(&mhi_cntrl->state_lock);
mutex_lock(&mhi_cntrl->state_lock);
/* Reset MMIO to signal host that the MHI_RESET is completed in endpoint */
mhi_ep_mmio_reset(mhi_cntrl);
cur_state = mhi_cntrl->mhi_state;
spin_unlock_bh(&mhi_cntrl->state_lock);
/*
* Only proceed further if the reset is due to SYS_ERR. The host will
@ -1014,6 +1014,8 @@ static void mhi_ep_reset_worker(struct work_struct *work)
*/
if (cur_state == MHI_STATE_SYS_ERR)
mhi_ep_power_up(mhi_cntrl);
mutex_unlock(&mhi_cntrl->state_lock);
}
/*
@ -1386,8 +1388,8 @@ int mhi_ep_register_controller(struct mhi_ep_cntrl *mhi_cntrl,
INIT_LIST_HEAD(&mhi_cntrl->st_transition_list);
INIT_LIST_HEAD(&mhi_cntrl->ch_db_list);
spin_lock_init(&mhi_cntrl->state_lock);
spin_lock_init(&mhi_cntrl->list_lock);
mutex_init(&mhi_cntrl->state_lock);
mutex_init(&mhi_cntrl->event_lock);
/* Set MHI version and AMSS EE before enumeration */

42
drivers/bus/mhi/ep/sm.c
View file

@ -63,24 +63,23 @@ int mhi_ep_set_m0_state(struct mhi_ep_cntrl *mhi_cntrl)
int ret;
/* If MHI is in M3, resume suspended channels */
spin_lock_bh(&mhi_cntrl->state_lock);
mutex_lock(&mhi_cntrl->state_lock);
old_state = mhi_cntrl->mhi_state;
if (old_state == MHI_STATE_M3)
mhi_ep_resume_channels(mhi_cntrl);
ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M0);
spin_unlock_bh(&mhi_cntrl->state_lock);
if (ret) {
mhi_ep_handle_syserr(mhi_cntrl);
return ret;
goto err_unlock;
}
/* Signal host that the device moved to M0 */
ret = mhi_ep_send_state_change_event(mhi_cntrl, MHI_STATE_M0);
if (ret) {
dev_err(dev, "Failed sending M0 state change event\n");
return ret;
goto err_unlock;
}
if (old_state == MHI_STATE_READY) {
@ -88,11 +87,14 @@ int mhi_ep_set_m0_state(struct mhi_ep_cntrl *mhi_cntrl)
ret = mhi_ep_send_ee_event(mhi_cntrl, MHI_EE_AMSS);
if (ret) {
dev_err(dev, "Failed sending AMSS EE event\n");
return ret;
goto err_unlock;
}
}
return 0;
err_unlock:
mutex_unlock(&mhi_cntrl->state_lock);
return ret;
}
int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl)
@ -100,13 +102,12 @@ int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl)
struct device *dev = &mhi_cntrl->mhi_dev->dev;
int ret;
spin_lock_bh(&mhi_cntrl->state_lock);
ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M3);
spin_unlock_bh(&mhi_cntrl->state_lock);
mutex_lock(&mhi_cntrl->state_lock);
ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M3);
if (ret) {
mhi_ep_handle_syserr(mhi_cntrl);
return ret;
goto err_unlock;
}
mhi_ep_suspend_channels(mhi_cntrl);
@ -115,10 +116,13 @@ int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl)
ret = mhi_ep_send_state_change_event(mhi_cntrl, MHI_STATE_M3);
if (ret) {
dev_err(dev, "Failed sending M3 state change event\n");
return ret;
goto err_unlock;
}
return 0;
err_unlock:
mutex_unlock(&mhi_cntrl->state_lock);
return ret;
}
int mhi_ep_set_ready_state(struct mhi_ep_cntrl *mhi_cntrl)
@ -127,22 +131,24 @@ int mhi_ep_set_ready_state(struct mhi_ep_cntrl *mhi_cntrl)
enum mhi_state mhi_state;
int ret, is_ready;
spin_lock_bh(&mhi_cntrl->state_lock);
mutex_lock(&mhi_cntrl->state_lock);
/* Ensure that the MHISTATUS is set to RESET by host */
mhi_state = mhi_ep_mmio_masked_read(mhi_cntrl, EP_MHISTATUS, MHISTATUS_MHISTATE_MASK);
is_ready = mhi_ep_mmio_masked_read(mhi_cntrl, EP_MHISTATUS, MHISTATUS_READY_MASK);
if (mhi_state != MHI_STATE_RESET || is_ready) {
dev_err(dev, "READY state transition failed. MHI host not in RESET state\n");
spin_unlock_bh(&mhi_cntrl->state_lock);
return -EIO;
ret = -EIO;
goto err_unlock;
}
ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_READY);
spin_unlock_bh(&mhi_cntrl->state_lock);
if (ret)
mhi_ep_handle_syserr(mhi_cntrl);
err_unlock:
mutex_unlock(&mhi_cntrl->state_lock);
return ret;
}

4
include/linux/mhi_ep.h
View file

@ -70,8 +70,8 @@ struct mhi_ep_db_info {
* @cmd_ctx_cache_phys: Physical address of the host command context cache
* @chdb: Array of channel doorbell interrupt info
* @event_lock: Lock for protecting event rings
* @list_lock: Lock for protecting state transition and channel doorbell lists
* @state_lock: Lock for protecting state transitions
* @list_lock: Lock for protecting state transition and channel doorbell lists
* @st_transition_list: List of state transitions
* @ch_db_list: List of queued channel doorbells
* @wq: Dedicated workqueue for handling rings and state changes
@ -117,8 +117,8 @@ struct mhi_ep_cntrl {
struct mhi_ep_db_info chdb[4];
struct mutex event_lock;
struct mutex state_lock;
spinlock_t list_lock;
spinlock_t state_lock;
struct list_head st_transition_list;
struct list_head ch_db_list;