[PATCH v2 29/30] cxlflash: Fix to avoid state change collision
Matthew R. Ochs
mrochs at linux.vnet.ibm.com
Thu Sep 17 03:08:19 AEST 2015
The adapter state machine is susceptible to missing and/or
corrupting state updates at runtime. This can lead to a variety
of unintended issues and is due to the lack of a serialization
mechanism to protect the adapter state.
Use an adapter-wide mutex to serialize state changes.
Signed-off-by: Matthew R. Ochs <mrochs at linux.vnet.ibm.com>
Signed-off-by: Manoj N. Kumar <manoj at linux.vnet.ibm.com>
Suggested-by: Brian King <brking at linux.vnet.ibm.com>
---
drivers/scsi/cxlflash/common.h | 1 +
drivers/scsi/cxlflash/main.c | 40 +++++++++++++++++++++++++++++++++------
drivers/scsi/cxlflash/superpipe.c | 7 ++++++-
3 files changed, 41 insertions(+), 7 deletions(-)
diff --git a/drivers/scsi/cxlflash/common.h b/drivers/scsi/cxlflash/common.h
index e6041b9..c9b1ec6 100644
--- a/drivers/scsi/cxlflash/common.h
+++ b/drivers/scsi/cxlflash/common.h
@@ -128,6 +128,7 @@ struct cxlflash_cfg {
bool tmf_active;
wait_queue_head_t reset_waitq;
enum cxlflash_state state;
+ struct mutex mutex;
};
struct afu_cmd {
diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
index 0487fac..a94340d 100644
--- a/drivers/scsi/cxlflash/main.c
+++ b/drivers/scsi/cxlflash/main.c
@@ -496,6 +496,7 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp)
struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)host->hostdata;
struct afu *afu = cfg->afu;
struct device *dev = &cfg->dev->dev;
+ enum cxlflash_state state;
struct afu_cmd *cmd;
u32 port_sel = scp->device->channel + 1;
int nseg, i, ncount;
@@ -525,7 +526,11 @@ static int cxlflash_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scp)
}
spin_unlock_irqrestore(&cfg->tmf_slock, lock_flags);
- switch (cfg->state) {
+ mutex_lock(&cfg->mutex);
+ state = cfg->state;
+ mutex_unlock(&cfg->mutex);
+
+ switch (state) {
case STATE_RESET:
dev_dbg_ratelimited(dev, "%s: device is in reset!\n", __func__);
rc = SCSI_MLQUEUE_HOST_BUSY;
@@ -722,7 +727,9 @@ static void cxlflash_remove(struct pci_dev *pdev)
cfg->tmf_slock);
spin_unlock_irqrestore(&cfg->tmf_slock, lock_flags);
+ mutex_lock(&cfg->mutex);
cfg->state = STATE_FAILTERM;
+ mutex_unlock(&cfg->mutex);
atomic_inc(&cfg->remove_active);
cxlflash_stop_term_user_contexts(cfg);
@@ -1811,12 +1818,13 @@ int cxlflash_afu_sync(struct afu *afu, ctx_hndl_t ctx_hndl_u,
int retry_cnt = 0;
static DEFINE_MUTEX(sync_active);
+ mutex_lock(&sync_active);
+ mutex_lock(&cfg->mutex);
if (cfg->state != STATE_NORMAL) {
pr_debug("%s: Sync not required! (%u)\n", __func__, cfg->state);
- return 0;
+ goto out;
}
- mutex_lock(&sync_active);
retry:
cmd = cmd_checkout(afu);
if (unlikely(!cmd)) {
@@ -1858,6 +1866,7 @@ retry:
(cmd->sa.host_use_b[0] & B_ERROR)))
rc = -1;
out:
+ mutex_unlock(&cfg->mutex);
mutex_unlock(&sync_active);
if (cmd)
cmd_checkin(cmd);
@@ -1900,6 +1909,7 @@ static int cxlflash_eh_device_reset_handler(struct scsi_cmnd *scp)
struct Scsi_Host *host = scp->device->host;
struct cxlflash_cfg *cfg = (struct cxlflash_cfg *)host->hostdata;
struct afu *afu = cfg->afu;
+ enum cxlflash_state state;
int rcr = 0;
pr_debug("%s: (scp=%p) %d/%d/%d/%llu "
@@ -1912,7 +1922,11 @@ static int cxlflash_eh_device_reset_handler(struct scsi_cmnd *scp)
get_unaligned_be32(&((u32 *)scp->cmnd)[3]));
retry:
- switch (cfg->state) {
+ mutex_lock(&cfg->mutex);
+ state = cfg->state;
+ mutex_unlock(&cfg->mutex);
+
+ switch (state) {
case STATE_NORMAL:
rcr = send_tmf(afu, scp, TMF_LUN_RESET);
if (unlikely(rcr))
@@ -1954,6 +1968,7 @@ static int cxlflash_eh_host_reset_handler(struct scsi_cmnd *scp)
get_unaligned_be32(&((u32 *)scp->cmnd)[2]),
get_unaligned_be32(&((u32 *)scp->cmnd)[3]));
+ mutex_lock(&cfg->mutex);
switch (cfg->state) {
case STATE_NORMAL:
cfg->state = STATE_RESET;
@@ -1967,7 +1982,9 @@ static int cxlflash_eh_host_reset_handler(struct scsi_cmnd *scp)
wake_up_all(&cfg->reset_waitq);
break;
case STATE_RESET:
+ mutex_unlock(&cfg->mutex);
wait_event(cfg->reset_waitq, cfg->state != STATE_RESET);
+ mutex_lock(&cfg->mutex);
if (cfg->state == STATE_NORMAL)
break;
/* fall through */
@@ -1975,6 +1992,7 @@ static int cxlflash_eh_host_reset_handler(struct scsi_cmnd *scp)
rc = FAILED;
break;
}
+ mutex_unlock(&cfg->mutex);
pr_debug("%s: returning rc=%d\n", __func__, rc);
return rc;
@@ -2312,10 +2330,11 @@ static void cxlflash_worker_thread(struct work_struct *work)
int port;
ulong lock_flags;
- /* Avoid MMIO if the device has failed */
+ mutex_lock(&cfg->mutex);
+ /* Avoid MMIO if the device has failed */
if (cfg->state != STATE_NORMAL)
- return;
+ goto out;
spin_lock_irqsave(cfg->host->host_lock, lock_flags);
@@ -2346,6 +2365,8 @@ static void cxlflash_worker_thread(struct work_struct *work)
if (atomic_dec_if_positive(&cfg->scan_host_needed) >= 0)
scsi_scan_host(cfg->host);
+out:
+ mutex_unlock(&cfg->mutex);
}
/**
@@ -2416,6 +2437,7 @@ static int cxlflash_probe(struct pci_dev *pdev,
INIT_WORK(&cfg->work_q, cxlflash_worker_thread);
cfg->lr_state = LINK_RESET_INVALID;
cfg->lr_port = -1;
+ mutex_init(&cfg->mutex);
mutex_init(&cfg->ctx_tbl_list_mutex);
mutex_init(&cfg->ctx_recovery_mutex);
init_rwsem(&cfg->ioctl_rwsem);
@@ -2503,7 +2525,9 @@ static pci_ers_result_t cxlflash_pci_error_detected(struct pci_dev *pdev,
switch (state) {
case pci_channel_io_frozen:
+ mutex_lock(&cfg->mutex);
cfg->state = STATE_RESET;
+ mutex_unlock(&cfg->mutex);
scsi_block_requests(cfg->host);
drain_ioctls(cfg);
rc = cxlflash_mark_contexts_error(cfg);
@@ -2514,7 +2538,9 @@ static pci_ers_result_t cxlflash_pci_error_detected(struct pci_dev *pdev,
stop_afu(cfg);
return PCI_ERS_RESULT_NEED_RESET;
case pci_channel_io_perm_failure:
+ mutex_lock(&cfg->mutex);
cfg->state = STATE_FAILTERM;
+ mutex_unlock(&cfg->mutex);
wake_up_all(&cfg->reset_waitq);
scsi_unblock_requests(cfg->host);
return PCI_ERS_RESULT_DISCONNECT;
@@ -2561,7 +2587,9 @@ static void cxlflash_pci_resume(struct pci_dev *pdev)
dev_dbg(dev, "%s: pdev=%p\n", __func__, pdev);
+ mutex_lock(&cfg->mutex);
cfg->state = STATE_NORMAL;
+ mutex_unlock(&cfg->mutex);
wake_up_all(&cfg->reset_waitq);
scsi_unblock_requests(cfg->host);
}
diff --git a/drivers/scsi/cxlflash/superpipe.c b/drivers/scsi/cxlflash/superpipe.c
index 9844788..c3aaadf 100644
--- a/drivers/scsi/cxlflash/superpipe.c
+++ b/drivers/scsi/cxlflash/superpipe.c
@@ -1229,10 +1229,15 @@ static const struct file_operations null_fops = {
static int check_state(struct cxlflash_cfg *cfg, bool ioctl)
{
struct device *dev = &cfg->dev->dev;
+ enum cxlflash_state state;
int rc = 0;
retry:
- switch (cfg->state) {
+ mutex_lock(&cfg->mutex);
+ state = cfg->state;
+ mutex_unlock(&cfg->mutex);
+
+ switch (state) {
case STATE_RESET:
dev_dbg(dev, "%s: Reset state, going to wait...\n", __func__);
if (ioctl)
--
2.1.0
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