[PATCH 3.18 053/183] cxl: Add timeout to process element commands

Greg Kroah-Hartman
2015-01-25T18:56:16Z

From: Ian Munsie <imunsie@au1.ibm.com>

commit a98e6e9f4e0224d85b4d951edc44af16dfe6094a upstream.

In the event that something goes wrong in the hardware and it is unable
to complete a process element comment we would end up polling forever,
effectively making the associated process unkillable.

This patch adds a timeout to the process element command code path, so
that we will give up if the hardware does not respond in a reasonable
time.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/misc/cxl/native.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -277,6 +277,7 @@ static int do_process_element_cmd(struct
u64 cmd, u64 pe_state)
{
u64 state;
+ unsigned long timeout = jiffies + (HZ * CXL_TIMEOUT);

WARN_ON(!ctx->afu->enabled);

@@ -286,6 +287,10 @@ static int do_process_element_cmd(struct
smp_mb();
cxl_p1n_write(ctx->afu, CXL_PSL_LLCMD_An, cmd | ctx->pe);
while (1) {
+ if (time_after_eq(jiffies, timeout)) {
+ dev_warn(&ctx->afu->dev, "WARNING: Process Element Command timed out!\n");
+ return -EBUSY;
+ }
state = be64_to_cpup(ctx->afu->sw_command_status);
if (state == ~0ULL) {
pr_err("cxl: Error adding process element to AFU\n");