| Message ID | 20091125213546.GA6168@rhlx01.hs-esslingen.de |
|---|---|
| State | Rejected, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Andreas Mohr <andi@lisas.de> Date: Wed, 25 Nov 2009 22:35:46 +0100 > Turns out that it's not very helpful to have a netconsole-deployed > network driver's interrupt handler message spew noise permanently > (see comment in patch). It's not even an illegal state, especially with shared interrupts. The warning should never be emitted. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- linux-2.6.30.9/drivers/net/b44.c.orig 2009-11-25 20:49:48.000000000 +0100 +++ linux-2.6.30.9/drivers/net/b44.c 2009-11-25 21:26:34.000000000 +0100 @@ -913,8 +913,18 @@ __b44_disable_ints(bp); __napi_schedule(&bp->napi); } else { - printk(KERN_ERR PFX "%s: Error, poll already scheduled\n", - dev->name); + /* netconsole fix!!: + * without ratelimiting, this message would: + * immediately find its way out to b44 netconsole -> + * new IRQ -> re-encounter failed napi_schedule_prep() + * -> error message -> ad nauseam -> box LOCKUP. + * See thread "r8169: avoid losing MSI interrupts" + * for further inspiration. */ + if (printk_ratelimit()) + printk(KERN_ERR PFX + "%s: Error, poll already scheduled; " + "istat 0x%x, imask 0x%x\n", + dev->name, istat, imask); } irq_ack:
Hello all, my OpenWrt MIPSEL ASUS WL-500gP v2 kept locking up during driver debugging with kobject debugging turned on (when debugging non-working drivers such as USB, ftdi_sio and usb_audio). Turns out that it's not very helpful to have a netconsole-deployed network driver's interrupt handler message spew noise permanently (see comment in patch). See http://bugzilla.kernel.org/show_bug.cgi?id=14691 for background information. Tested on 2.6.30.9 and working (now normal debug messages manage to come through, too, yet box still locked up, simply due to excessive _normal_ log messages such as kobject logging, but that's _expected_ and user-correctable). checkpatch.pl'd, applies cleanly to -rc8. Likely -stable candidate material. r8169 (and perhaps other netconsole-capable drivers?) might need such a correction, too, if the if (likely(napi_schedule_prep(&tp->napi))) __napi_schedule(&tp->napi); else if (netif_msg_intr(tp)) { printk(KERN_INFO "%s: interrupt %04x in poll\n", dev->name, status); } is similarly problematic. BTW: this patch here is to be seen separate from the r8169 interrupt handler rework as discussed at "r8169: avoid losing MSI interrupts", since even with a "working" interrupt handler (i.e. one that closes the "new interrupt" race window, which the one in b44 currently probably doesn't) such error messages have a fatal feedback loop in the case of netconsole deployment. Thanks, Signed-off-by: Andreas Mohr <andi@lisas.de> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html