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SubjectRe: [PATCH v2 1/2] x86/mm/pat, drivers/infiniband/ipath: replace WARN() with pr_warn()

* Luis R. Rodriguez <mcgrof@do-not-panic.com> wrote:

> From: "Luis R. Rodriguez" <mcgrof@suse.com>
>
> WARN() may confuse users, fix that. ipath_init_one() is part the
> device's probe so this would only be triggered if a corresponding
> device was found.
>
> Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
> ---
> drivers/infiniband/hw/ipath/ipath_driver.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/infiniband/hw/ipath/ipath_driver.c b/drivers/infiniband/hw/ipath/ipath_driver.c
> index 2d7e503..871dbe5 100644
> --- a/drivers/infiniband/hw/ipath/ipath_driver.c
> +++ b/drivers/infiniband/hw/ipath/ipath_driver.c
> @@ -31,6 +31,8 @@
> * SOFTWARE.
> */
>
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> #include <linux/sched.h>
> #include <linux/spinlock.h>
> #include <linux/idr.h>
> @@ -399,8 +401,8 @@ static int ipath_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> u32 bar0 = 0, bar1 = 0;
>
> #ifdef CONFIG_X86_64
> - if (WARN(pat_enabled(),
> - "ipath needs PAT disabled, boot with nopat kernel parameter\n")) {
> + if (pat_enabled()) {
> + pr_warn("ipath needs PAT disabled, boot with nopat kernel parameter\n");
> ret = -ENODEV;
> goto bail;
> }

So driver init will always fail with this on modern kernels.

Btw., on a second thought, ipath uses MTRRs to enable WC:

ret = ipath_enable_wc(dd);
if (ret)
ret = 0;

Note how it ignores any failures - the driver still works even if WC was not
enabled.

So why don't you simply extend ipath_enable_wc() to generate the warning message
and return -EINVAL - which still keeps the driver working on modern kernels?

Just inform the user about 'nopat' if he wants WC for this driver.

Thanks,

Ingo


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