Re: Linux 5.15-rc1

From: Bjorn Helgaas
Date: Mon Sep 13 2021 - 19:46:23 EST

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In reply to: Dave Jones: "Re: Linux 5.15-rc1"
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On Mon, Sep 13, 2021 at 10:18:18AM -0400, Dave Jones wrote:
> On Sun, Sep 12, 2021 at 04:58:27PM -0700, Linus Torvalds wrote:
> > So 5.15 isn't shaping up to be a particularly large release, at least
> > in number of commits. At only just over 10k non-merge commits, this is
> > in fact the smallest rc1 we have had in the 5.x series. We're usually
> > hovering in the 12-14k commit range.
>
> This release takes over two minutes longer to boot on one my
> machines than 5.14. The time just seems to be unaccounted for, even
> with initcall_debug

> ...
> [ 2.194093] pci 0000:01:00.0: calling quirk_f0_vpd_link+0x0/0x60 @ 1
> [ 2.194097] pci 0000:01:00.0: quirk_f0_vpd_link+0x0/0x60 took 0 usecs
> [ 2.194100] pci 0000:01:00.0: [8086:10fb] type 00 class 0x020000
> [ 2.194109] pci 0000:01:00.0: reg 0x10: [mem 0xd0080000-0xd00fffff 64bit pref]
> [ 2.194113] pci 0000:01:00.0: reg 0x18: [io 0xe020-0xe03f]
> [ 2.194121] pci 0000:01:00.0: reg 0x20: [mem 0xd0104000-0xd0107fff 64bit pref]
> [ 2.194126] pci 0000:01:00.0: reg 0x30: [mem 0xdfd80000-0xdfdfffff pref]
> [ 2.194136] pci 0000:01:00.0: calling quirk_igfx_skip_te_disable+0x0/0x50 @ 1
> [ 2.194139] pci 0000:01:00.0: quirk_igfx_skip_te_disable+0x0/0x50 took 0 usecs
> [ 2.194164] pci 0000:01:00.0: PME# supported from D0 D3hot D3cold
>
> * stall here for 86 seconds *
>
> [ 88.675114] pci 0000:01:00.0: reg 0x184: [mem 0x00000000-0x00003fff 64bit pref]
> ...

> 7bac54497c3e3b2ca37b7043f1fa78586540f10e is the first bad commit
> commit 7bac54497c3e3b2ca37b7043f1fa78586540f10e
> Author: Heiner Kallweit <hkallweit1@xxxxxxxxx>
> Date: Sun Aug 8 19:22:52 2021 +0200
>
> PCI/VPD: Determine VPD size in pci_vpd_init()
>
> Determine VPD size in pci_vpd_init().
>
> Quirks set dev->vpd.len to a non-zero value, so they cause us to skip the
> dynamic size calculation. Prerequisite is that we move the quirks from
> FINAL to HEADER so they are run before pci_vpd_init().
>
> Link: https://lore.kernel.org/r/cc4a6538-557a-294d-4f94-e6d1d3c91589@xxxxxxxxx
> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>
>
> Which unfortunately doesn't revert cleanly I can't test it reverted in
> isolation.
>
> My guess is there's something quirky about the PCI bus on this machine
> that causes stalls until we hit timeout, but I'm not sure where to begin
> debugging this.

Sorry for the inconvenience of this, and thank you very much for doing
the bisection to track it down.

We *could* revert 7bac54497c3e, but it'd be messy because a bunch of
follow-up stuff depends on it.

I propose something like the patch below. Would you mind trying it
out?

commit 4ede9949b93c ("PCI/VPD: Defer VPD sizing until first access")
Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Date: Mon Sep 13 16:13:26 2021 -0500

PCI/VPD: Defer VPD sizing until first access

7bac54497c3e ("PCI/VPD: Determine VPD size in pci_vpd_init()") reads VPD at
enumeration-time to find the size. But this is quite slow, and we don't
need the size until we actually need data from VPD. Dave reported a boot
slowdown of more than two minutes [1].

Defer the VPD sizing until a driver or the user requests information from
VPD. If devices are quirked because VPD is known not to work, clear the
vpd.cap pointer so we don't access it at all.

[1] https://lore.kernel.org/r/20210913141818.GA27911@xxxxxxxxxxxxxxxxx/
Fixes: 7bac54497c3e ("PCI/VPD: Determine VPD size in pci_vpd_init()")
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
index 25557b272a4f..ca823ceee10c 100644
--- a/drivers/pci/vpd.c
+++ b/drivers/pci/vpd.c
@@ -46,13 +46,12 @@ static struct pci_dev *pci_get_func0_dev(struct pci_dev *dev)
}

#define PCI_VPD_MAX_SIZE (PCI_VPD_ADDR_MASK + 1)
-#define PCI_VPD_SZ_INVALID UINT_MAX

/**
* pci_vpd_size - determine actual size of Vital Product Data
* @dev: pci device struct
*/
-static size_t pci_vpd_size(struct pci_dev *dev)
+static void pci_vpd_size(struct pci_dev *dev)
{
size_t off = 0, size;
unsigned char tag, header[1+2]; /* 1 byte tag, 2 bytes length */
@@ -71,7 +70,7 @@ static size_t pci_vpd_size(struct pci_dev *dev)
if (pci_read_vpd(dev, off + 1, 2, &header[1]) != 2) {
pci_warn(dev, "failed VPD read at offset %zu\n",
off + 1);
- return off ?: PCI_VPD_SZ_INVALID;
+ goto finish;
}
size = pci_vpd_lrdt_size(header);
if (off + size > PCI_VPD_MAX_SIZE)
@@ -87,16 +86,19 @@ static size_t pci_vpd_size(struct pci_dev *dev)

off += PCI_VPD_SRDT_TAG_SIZE + size;
if (tag == PCI_VPD_STIN_END) /* End tag descriptor */
- return off;
+ goto finish;
}
}
- return off;
+ goto finish;

error:
pci_info(dev, "invalid VPD tag %#04x (size %zu) at offset %zu%s\n",
header[0], size, off, off == 0 ?
"; assume missing optional EEPROM" : "");
- return off ?: PCI_VPD_SZ_INVALID;
+finish:
+ dev->vpd.len = off;
+ if (off == 0)
+ dev->vpd.cap = 0; /* No VPD at all */
}

/*
@@ -145,9 +147,6 @@ static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
loff_t end = pos + count;
u8 *buf = arg;

- if (!vpd->cap)
- return -ENODEV;
-
if (pos < 0)
return -EINVAL;

@@ -206,9 +205,6 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
loff_t end = pos + count;
int ret = 0;

- if (!vpd->cap)
- return -ENODEV;
-
if (pos < 0 || (pos & 3) || (count & 3))
return -EINVAL;

@@ -244,12 +240,6 @@ void pci_vpd_init(struct pci_dev *dev)
{
dev->vpd.cap = pci_find_capability(dev, PCI_CAP_ID_VPD);
mutex_init(&dev->vpd.lock);
-
- if (!dev->vpd.len)
- dev->vpd.len = pci_vpd_size(dev);
-
- if (dev->vpd.len == PCI_VPD_SZ_INVALID)
- dev->vpd.cap = 0;
}

static ssize_t vpd_read(struct file *filp, struct kobject *kobj,
@@ -294,25 +284,29 @@ const struct attribute_group pci_dev_vpd_attr_group = {

void *pci_vpd_alloc(struct pci_dev *dev, unsigned int *size)
{
- unsigned int len = dev->vpd.len;
+ struct pci_vpd *vpd = &dev->vpd;
+ unsigned int len;
void *buf;
int cnt;

- if (!dev->vpd.cap)
+ if (!vpd->cap)
return ERR_PTR(-ENODEV);

buf = kmalloc(len, GFP_KERNEL);
if (!buf)
return ERR_PTR(-ENOMEM);

- cnt = pci_read_vpd(dev, 0, len, buf);
+ if (vpd->len == 0)
+ pci_vpd_size(dev);
+
+ cnt = pci_read_vpd(dev, 0, vpd->len, buf);
if (cnt != len) {
kfree(buf);
return ERR_PTR(-EIO);
}

if (size)
- *size = len;
+ *size = vpd->len;

return buf;
}
@@ -374,6 +368,7 @@ static int pci_vpd_find_info_keyword(const u8 *buf, unsigned int off,
*/
ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf)
{
+ struct pci_vpd *vpd;
ssize_t ret;

if (dev->dev_flags & PCI_DEV_FLAGS_VPD_REF_F0) {
@@ -381,11 +376,27 @@ ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf)
if (!dev)
return -ENODEV;

+ vpd = &dev->vpd;
+ if (!vpd->cap) {
+ pci_dev_put(dev);
+ return -ENODEV;
+ }
+
+ if (vpd->len == 0)
+ pci_vpd_size(dev);
+
ret = pci_vpd_read(dev, pos, count, buf);
pci_dev_put(dev);
return ret;
}

+ vpd = &dev->vpd;
+ if (!vpd->cap)
+ return -ENODEV;
+
+ if (vpd->len == 0)
+ pci_vpd_size(dev);
+
return pci_vpd_read(dev, pos, count, buf);
}
EXPORT_SYMBOL(pci_read_vpd);
@@ -399,6 +410,7 @@ EXPORT_SYMBOL(pci_read_vpd);
*/
ssize_t pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count, const void *buf)
{
+ struct pci_vpd *vpd;
ssize_t ret;

if (dev->dev_flags & PCI_DEV_FLAGS_VPD_REF_F0) {
@@ -406,11 +418,26 @@ ssize_t pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count, const void
if (!dev)
return -ENODEV;

+ vpd = &dev->vpd;
+ if (!vpd->cap) {
+ pci_dev_put(dev);
+ return -ENODEV;
+ }
+
+ if (vpd->len == 0)
+ pci_vpd_size(dev);
+
ret = pci_vpd_write(dev, pos, count, buf);
pci_dev_put(dev);
return ret;
}

+ if (!vpd->cap)
+ return -ENODEV;
+
+ if (vpd->len == 0)
+ pci_vpd_size(dev);
+
return pci_vpd_write(dev, pos, count, buf);
}
EXPORT_SYMBOL(pci_write_vpd);
@@ -500,27 +527,27 @@ DECLARE_PCI_FIXUP_CLASS_EARLY(PCI_VENDOR_ID_INTEL, PCI_ANY_ID,
*/
static void quirk_blacklist_vpd(struct pci_dev *dev)
{
- dev->vpd.len = PCI_VPD_SZ_INVALID;
+ dev->vpd.cap = 0;
pci_warn(dev, FW_BUG "disabling VPD access (can't determine size of non-standard VPD format)\n");
}
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LSI_LOGIC, 0x0060, quirk_blacklist_vpd);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LSI_LOGIC, 0x007c, quirk_blacklist_vpd);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LSI_LOGIC, 0x0413, quirk_blacklist_vpd);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LSI_LOGIC, 0x0078, quirk_blacklist_vpd);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LSI_LOGIC, 0x0079, quirk_blacklist_vpd);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LSI_LOGIC, 0x0073, quirk_blacklist_vpd);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LSI_LOGIC, 0x0071, quirk_blacklist_vpd);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LSI_LOGIC, 0x005b, quirk_blacklist_vpd);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LSI_LOGIC, 0x002f, quirk_blacklist_vpd);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LSI_LOGIC, 0x005d, quirk_blacklist_vpd);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_LSI_LOGIC, 0x005f, quirk_blacklist_vpd);
-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATTANSIC, PCI_ANY_ID, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LSI_LOGIC, 0x0060, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LSI_LOGIC, 0x007c, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LSI_LOGIC, 0x0413, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LSI_LOGIC, 0x0078, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LSI_LOGIC, 0x0079, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LSI_LOGIC, 0x0073, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LSI_LOGIC, 0x0071, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LSI_LOGIC, 0x005b, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LSI_LOGIC, 0x002f, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LSI_LOGIC, 0x005d, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_LSI_LOGIC, 0x005f, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATTANSIC, PCI_ANY_ID, quirk_blacklist_vpd);
/*
* The Amazon Annapurna Labs 0x0031 device id is reused for other non Root Port
* device types, so the quirk is registered for the PCI_CLASS_BRIDGE_PCI class.
*/
-DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_VENDOR_ID_AMAZON_ANNAPURNA_LABS, 0x0031,
- PCI_CLASS_BRIDGE_PCI, 8, quirk_blacklist_vpd);
+DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_AMAZON_ANNAPURNA_LABS, 0x0031,
+ PCI_CLASS_BRIDGE_PCI, 8, quirk_blacklist_vpd);

static void quirk_chelsio_extend_vpd(struct pci_dev *dev)
{
@@ -545,7 +572,7 @@ static void quirk_chelsio_extend_vpd(struct pci_dev *dev)
dev->vpd.len = 2048;
}

-DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_CHELSIO, PCI_ANY_ID,
- quirk_chelsio_extend_vpd);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_CHELSIO, PCI_ANY_ID,
+ quirk_chelsio_extend_vpd);

#endif

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