[PATCH 06/18] PCI: endpoint: functions/pci-epf-test: Do not reset *command* inadvertently

Kishon Vijay Abraham I
2017-08-18T14:57:58Z

pci_epf_test_cmd_handler() is the delayed work function which reads
*command* (set by the host) and performs various actions requested
by the host periodically. If the value in *command* is '0', it
goes to the reset_handler where it resets *command* to '0' and queues
pci_epf_test_cmd_handler().
However if the host writes a value to the *command* just after the
pci-epf-test driver checks *command* for '0' and before the control goes
to reset_handler, the *command* will be reset to '0' and the pci-epf-test
driver won't be able to perform the actions requested by the host.
Fix it here by not resetting the *command* in the reset_handler.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
---
drivers/pci/endpoint/functions/pci-epf-test.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index 5cbc05a0762d..1a27d7950f2c 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -263,22 +263,26 @@ static void pci_epf_test_cmd_handler(struct work_struct *work)
int ret;
u8 irq;
u8 msi_count;
+ u32 command;
struct pci_epf_test *epf_test = container_of(work, struct pci_epf_test,
cmd_handler.work);
struct pci_epf *epf = epf_test->epf;
struct pci_epc *epc = epf->epc;
volatile struct pci_epf_test_reg *reg = epf_test->reg[0];

- if (!reg->command)
+ command = reg->command;
+ if (!command)
goto reset_handler;

- if (reg->command & COMMAND_RAISE_LEGACY_IRQ) {
+ reg->command = 0;
+
+ if (command & COMMAND_RAISE_LEGACY_IRQ) {
reg->status = STATUS_IRQ_RAISED;
pci_epc_raise_irq(epc, PCI_EPC_IRQ_LEGACY, 0);
goto reset_handler;
}

- if (reg->command & COMMAND_WRITE) {
+ if (command & COMMAND_WRITE) {
ret = pci_epf_test_write(epf_test);
if (ret)
reg->status |= STATUS_WRITE_FAIL;
@@ -288,7 +292,7 @@ static void pci_epf_test_cmd_handler(struct work_struct *work)
goto reset_handler;
}

- if (reg->command & COMMAND_READ) {
+ if (command & COMMAND_READ) {
ret = pci_epf_test_read(epf_test);
if (!ret)
reg->status |= STATUS_READ_SUCCESS;
@@ -298,7 +302,7 @@ static void pci_epf_test_cmd_handler(struct work_struct *work)
goto reset_handler;
}

- if (reg->command & COMMAND_COPY) {
+ if (command & COMMAND_COPY) {
ret = pci_epf_test_copy(epf_test);
if (!ret)
reg->status |= STATUS_COPY_SUCCESS;
@@ -308,9 +312,9 @@ static void pci_epf_test_cmd_handler(struct work_struct *work)
goto reset_handler;
}

- if (reg->command & COMMAND_RAISE_MSI_IRQ) {
+ if (command & COMMAND_RAISE_MSI_IRQ) {
msi_count = pci_epc_get_msi(epc);
- irq = (reg->command & MSI_NUMBER_MASK) >> MSI_NUMBER_SHIFT;
+ irq = (command & MSI_NUMBER_MASK) >> MSI_NUMBER_SHIFT;
if (irq > msi_count || msi_count <= 0)
goto reset_handler;
reg->status = STATUS_IRQ_RAISED;
@@ -319,8 +323,6 @@ static void pci_epf_test_cmd_handler(struct work_struct *work)
}

reset_handler:
- reg->command = 0;
-
queue_delayed_work(kpcitest_workqueue, &epf_test->cmd_handler,
msecs_to_jiffies(1));
}
--
2.11.0