On 1/9/2026 12:03 PM, Dave Jiang wrote:
>
>
> On 1/9/26 9:07 AM, Ben Cheatham wrote:
>> Add a library API for clearing and injecting poison into a CXL memory
>> device through the CXL debugfs.
>>
>> This API will be used by the 'cxl-inject-error' and 'cxl-clear-error'
>> commands in later commits.
>>
>> Signed-off-by: Ben Cheatham <[email protected]>
>> ---
>> cxl/lib/libcxl.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++
>> cxl/lib/libcxl.sym | 3 ++
>> cxl/libcxl.h | 3 ++
>> 3 files changed, 89 insertions(+)
>>
>> diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
>> index 27ff037..deebf7f 100644
>> --- a/cxl/lib/libcxl.c
>> +++ b/cxl/lib/libcxl.c
>> @@ -5046,3 +5046,86 @@ CXL_EXPORT struct cxl_cmd
>> *cxl_cmd_new_set_alert_config(struct cxl_memdev *memde
>> {
>> return cxl_cmd_new_generic(memdev, CXL_MEM_COMMAND_ID_SET_ALERT_CONFIG);
>> }
>> +
>> +CXL_EXPORT bool cxl_memdev_has_poison_injection(struct cxl_memdev *memdev)
>> +{
>> + struct cxl_ctx *ctx = memdev->ctx;
>> + size_t path_len, len;
>> + bool exists = true;
>> + char *path;
>> + int rc;
>> +
>> + if (!ctx->cxl_debugfs)
>> + return false;
>> +
>> + path_len = strlen(ctx->cxl_debugfs) + 100;
>
> Same comment about PATH_MAX.
I'll change it (here and everywhere else).
>
>> + path = calloc(path_len, sizeof(char));
>> + if (!path)
>> + return false;
>> +
>> + len = snprintf(path, path_len, "%s/%s/inject_poison", ctx->cxl_debugfs,
>> + cxl_memdev_get_devname(memdev));
>> + if (len >= path_len) {
>> + err(ctx, "%s: buffer too small\n",
>> + cxl_memdev_get_devname(memdev));
>> + free(path);
>> + return false;
>
> I think I saw in an earlier patch that you were using goto to filter error
> exit point. So may as well make it consistent and do it here as well.
Sure, I'll update this and the function below. I already screwed up one of the
return paths last revision so
it's probably warranted.
>
>> + }
>> +
>> + rc = access(path, F_OK);
>> + if (rc)
>> + exists = false;
>> +
>> + free(path);
>> + return exists;
>> +}
>> +
>> +static int cxl_memdev_poison_action(struct cxl_memdev *memdev, size_t dpa,
>> + bool clear)
>> +{
>> + struct cxl_ctx *ctx = memdev->ctx;
>> + size_t path_len, len;
>> + char addr[32];
>> + char *path;
>> + int rc;
>> +
>> + if (!ctx->cxl_debugfs)
>> + return -ENOENT;
>> +
>> + path_len = strlen(ctx->cxl_debugfs) + 100;
>
> same comment about path len
>
>> + path = calloc(path_len, sizeof(char));
>> + if (!path)
>> + return -ENOMEM;
>> +
>> + len = snprintf(path, path_len, "%s/%s/%s", ctx->cxl_debugfs,
>> + cxl_memdev_get_devname(memdev),
>> + clear ? "clear_poison" : "inject_poison");
>> + if (len >= path_len) {
>> + err(ctx, "%s: buffer too small\n",
>> + cxl_memdev_get_devname(memdev));
>> + free(path);
>> + return -ENOMEM;
>
> same comment about error paths
>
> DJ
>
>> + }
>> +
>> + len = snprintf(addr, sizeof(addr), "0x%lx\n", dpa);
>> + if (len >= sizeof(addr)) {
>> + err(ctx, "%s: buffer too small\n",
>> + cxl_memdev_get_devname(memdev));
>> + free(path);
>> + return -ENOMEM;
>> + }
>> +
>> + rc = sysfs_write_attr(ctx, path, addr);
>> + free(path);
>> + return rc;
>> +}
>> +
>> +CXL_EXPORT int cxl_memdev_inject_poison(struct cxl_memdev *memdev, size_t
>> addr)
>> +{
>> + return cxl_memdev_poison_action(memdev, addr, false);
>> +}
>> +
>> +CXL_EXPORT int cxl_memdev_clear_poison(struct cxl_memdev *memdev, size_t
>> addr)
>> +{
>> + return cxl_memdev_poison_action(memdev, addr, true);
>> +}
>> diff --git a/cxl/lib/libcxl.sym b/cxl/lib/libcxl.sym
>> index c683b83..c636edb 100644
>> --- a/cxl/lib/libcxl.sym
>> +++ b/cxl/lib/libcxl.sym
>> @@ -309,4 +309,7 @@ global:
>> cxl_protocol_error_get_num;
>> cxl_protocol_error_get_str;
>> cxl_dport_protocol_error_inject;
>> + cxl_memdev_has_poison_injection;
>> + cxl_memdev_inject_poison;
>> + cxl_memdev_clear_poison;
>> } LIBCXL_10;
>> diff --git a/cxl/libcxl.h b/cxl/libcxl.h
>> index faef62e..4d035f0 100644
>> --- a/cxl/libcxl.h
>> +++ b/cxl/libcxl.h
>> @@ -105,6 +105,9 @@ int cxl_memdev_read_label(struct cxl_memdev *memdev,
>> void *buf, size_t length,
>> size_t offset);
>> int cxl_memdev_write_label(struct cxl_memdev *memdev, void *buf, size_t
>> length,
>> size_t offset);
>> +bool cxl_memdev_has_poison_injection(struct cxl_memdev *memdev);
>> +int cxl_memdev_inject_poison(struct cxl_memdev *memdev, size_t dpa);
>> +int cxl_memdev_clear_poison(struct cxl_memdev *memdev, size_t dpa);
>> struct cxl_cmd *cxl_cmd_new_get_fw_info(struct cxl_memdev *memdev);
>> unsigned int cxl_cmd_fw_info_get_num_slots(struct cxl_cmd *cmd);
>> unsigned int cxl_cmd_fw_info_get_active_slot(struct cxl_cmd *cmd);
>
