netdev - sblk->status_tag on drivers/net/ethernet/broadcom/tg3.c

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAD6G_RQVD7=v7b6S-muiZBYV7PEykTHOTM23i-BL=wcA5z=4Qg@mail.gmail.com>
Date:	Tue, 4 Mar 2014 23:09:33 +0530
From:	Jagan Teki <jagannadh.teki@...il.com>
To:	netdev@...r.kernel.org
Cc:	Nithin Nayak Sujir <nsujir@...adcom.com>,
	Michael Chan <mchan@...adcom.com>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>
Subject: sblk->status_tag on drivers/net/ethernet/broadcom/tg3.c

Hi All,

I have a board setup with PCIe host bridge links to BCRM NIC/tg3 EP.

I'm verifying legacy INT# for ifconfig up operation, typically for
link up EP trigger an interrupt as
Assert_INT# and PCIe RC driver ISR will called and then EP ISR will
clear and send Dessert_INT#

But I got the continues interrupts from EP which will keep ISR's in
both PCIe RC and EP in busy loop.

Log dump:
# ifconfig eth0 172.16.0.2 up
RC: handler
tg3_interrupt_tagged: write status = 0x1
RC: handler
tg3_interrupt_tagged: write status = 0x1
RC: handler
tg3_interrupt_tagged: write status = 0x1
RC: handler
tg3_interrupt_tagged: write status = 0x1
............................
..............

I debugged further on to EP driver where I could see there is
interrupt re-enabling is happining
by writing 0x0 to onto MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW

Debug code:
static irqreturn_t tg3_interrupt_tagged(int irq, void *dev_id)
{
      ...................
      printk(" ++status_tag = 0x%x", sblk->status_tag);
      .......................

      tw32_mailbox_f(MAILBOX_INTERRUPT_0 + TG3_64BIT_REG_LOW, 0x00000001);
      printk(" write status = 0x%x", tr32(MAILBOX_INTERRUPT_0 +
TG3_64BIT_REG_LOW));
      ..................
      tnapi->last_irq_tag = sblk->status_tag;
      printk(" --status_tag = 0x%x\n", tnapi->last_irq_tag);
}

static int tg3_poll(struct napi_struct *napi, int budget)
{

               if (tg3_flag(tp, TAGGED_STATUS)) {
                        /* tp->last_tag is used in tg3_int_reenable() below
                         * to tell the hw how much work has been processed,
                         * so we must read it before checking for more work.
                         */
                        tnapi->last_tag = sblk->status_tag;
                        tnapi->last_irq_tag = tnapi->last_tag;
                        rmb();
                } else
                        sblk->status &= ~SD_STATUS_UPDATED;

                printk(" tag = 0x%x\n", sblk->status_tag);
                if (likely(!tg3_has_work(tnapi))) {
                        napi_complete(napi);
                        printk("calling tg3_int_reenable\n");
                        tg3_int_reenable(tnapi);
                        break;
              }
}

static void tg3_int_reenable(struct tg3_napi *tnapi)
{
        struct tg3 *tp = tnapi->tp;

        printk("%s val = 0x%x\n", __func__, tnapi->last_tag << 24);
        tw32_mailbox(tnapi->int_mbox, tnapi->last_tag << 24);
        ..............................
}

Log dump:

# ifconfig eth0 172.16.0.2 up
RC: handler
tg3_interrupt_tagged: ++status_tag = 0x0 write status = 0x1 --status_tag = 0x0
RC: handler
tg3_interrupt_tagged: write status = 0x1
RC: handler
tg3_interrupt_tagged: write status = 0x1
RC: handler
tg3_interrupt_tagged: write status = 0x1
............................
..............








thanks!
-- 
Jagan.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html