[PATCH 2/7] CXL: Add timeout to process element commands

From: Ian Munsie
Date: Mon Dec 08 2014 - 03:18:50 EST

From: Ian Munsie <imunsie@xxxxxxxxxxx>

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

Signed-off-by: Ian Munsie <imunsie@xxxxxxxxxxx>
drivers/misc/cxl/native.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
index 1001cf4..f2b37b4 100644
--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -277,6 +277,7 @@ static int do_process_element_cmd(struct cxl_context *ctx,
u64 cmd, u64 pe_state)
u64 state;
+ unsigned long timeout = jiffies + (HZ * CXL_TIMEOUT);


@@ -286,6 +287,10 @@ static int do_process_element_cmd(struct cxl_context *ctx,
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");

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