| Message ID | 1555217391-3552-1-git-send-email-hofrat@osadl.org (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
| Series | [1/3,RFC] ARM: mvebu: at least warn on kzalloc failure | expand |
On Sun, Apr 14, 2019 at 06:49:49AM +0200, Nicholas Mc Guire wrote: > Although it is very unlikely that the allocation during init would > fail any such failure should point to the original cause rather > than waiting for a null-pointer dereference to splat. > > Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> > --- > > Problem located with experimental coccinelle script > > While this will not really help much - but kzalloc failures should not > go unhandled. Sorry, no, not like this. With this patch, rather than getting an oops and a stacktrace which people can capture and email, we instead end up getting a warning line, a stack trace, followed by an oops containing another stack trace. We _already_ have problems getting people to send us kernel message debug information without editing out what they deem to be "unnecessary verbage", like all those numbers and function names that comprise a stack trace. We don't need yet more of that stuff, especially when it is redundant. So, I think throwing WARN_ON() at this case is way too excessive, and will only have a detrimental effect on the reports we receive - and that is extremely important. IMHO, A better solution would be to just print a warning, rather than causing the kernel to print several kB of needless messages. if (!new_compat) pr_err("new_compat allocation failure in %s()\n", __func__); > > Patch was compile-tested: mvebu_v7_defconfig (implies MACH_MVEBU_ANY=y) > (with some unrelated sparse warnings about missing syscalls) > > Patch is against 5.1-rc4 (localversion-next is 20190412) > > arch/arm/mach-mvebu/board-v7.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm/mach-mvebu/board-v7.c b/arch/arm/mach-mvebu/board-v7.c > index 0b10acd..37f8cb6 100644 > --- a/arch/arm/mach-mvebu/board-v7.c > +++ b/arch/arm/mach-mvebu/board-v7.c > @@ -128,6 +128,7 @@ static void __init i2c_quirk(void) > struct property *new_compat; > > new_compat = kzalloc(sizeof(*new_compat), GFP_KERNEL); > + WARN_ON(!new_compat); > > new_compat->name = kstrdup("compatible", GFP_KERNEL); > new_compat->length = sizeof("marvell,mv78230-a0-i2c"); > -- > 2.1.4 > >
On Sun, Apr 14, 2019 at 06:26:02PM +0100, Russell King - ARM Linux admin wrote: > On Sun, Apr 14, 2019 at 06:49:49AM +0200, Nicholas Mc Guire wrote: > > Although it is very unlikely that the allocation during init would > > fail any such failure should point to the original cause rather > > than waiting for a null-pointer dereference to splat. > > > > Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> > > --- > > > > Problem located with experimental coccinelle script > > > > While this will not really help much - but kzalloc failures should not > > go unhandled. > > Sorry, no, not like this. > ok - well I wsa not sure about it either - it just seems wrong to leave a possible allocation failure without any response. The issue of generating excessive outout make sense - so will fix it up to a pr_err() and resend. thx! hofrat > With this patch, rather than getting an oops and a stacktrace which > people can capture and email, we instead end up getting a warning > line, a stack trace, followed by an oops containing another stack > trace. > > We _already_ have problems getting people to send us kernel message > debug information without editing out what they deem to be "unnecessary > verbage", like all those numbers and function names that comprise a > stack trace. We don't need yet more of that stuff, especially when it > is redundant. > > So, I think throwing WARN_ON() at this case is way too excessive, and > will only have a detrimental effect on the reports we receive - and > that is extremely important. > > IMHO, A better solution would be to just print a warning, rather than > causing the kernel to print several kB of needless messages. > > if (!new_compat) > pr_err("new_compat allocation failure in %s()\n", > __func__); > > > > > Patch was compile-tested: mvebu_v7_defconfig (implies MACH_MVEBU_ANY=y) > > (with some unrelated sparse warnings about missing syscalls) > > > > Patch is against 5.1-rc4 (localversion-next is 20190412) > > > > arch/arm/mach-mvebu/board-v7.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/arm/mach-mvebu/board-v7.c b/arch/arm/mach-mvebu/board-v7.c > > index 0b10acd..37f8cb6 100644 > > --- a/arch/arm/mach-mvebu/board-v7.c > > +++ b/arch/arm/mach-mvebu/board-v7.c > > @@ -128,6 +128,7 @@ static void __init i2c_quirk(void) > > struct property *new_compat; > > > > new_compat = kzalloc(sizeof(*new_compat), GFP_KERNEL); > > + WARN_ON(!new_compat); > > > > new_compat->name = kstrdup("compatible", GFP_KERNEL); > > new_compat->length = sizeof("marvell,mv78230-a0-i2c"); > > -- > > 2.1.4 > > > > > > -- > RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ > FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up > According to speedtest.net: 11.9Mbps down 500kbps up
diff --git a/arch/arm/mach-mvebu/board-v7.c b/arch/arm/mach-mvebu/board-v7.c index 0b10acd..37f8cb6 100644 --- a/arch/arm/mach-mvebu/board-v7.c +++ b/arch/arm/mach-mvebu/board-v7.c @@ -128,6 +128,7 @@ static void __init i2c_quirk(void) struct property *new_compat; new_compat = kzalloc(sizeof(*new_compat), GFP_KERNEL); + WARN_ON(!new_compat); new_compat->name = kstrdup("compatible", GFP_KERNEL); new_compat->length = sizeof("marvell,mv78230-a0-i2c");
Although it is very unlikely that the allocation during init would fail any such failure should point to the original cause rather than waiting for a null-pointer dereference to splat. Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org> --- Problem located with experimental coccinelle script While this will not really help much - but kzalloc failures should not go unhandled. Patch was compile-tested: mvebu_v7_defconfig (implies MACH_MVEBU_ANY=y) (with some unrelated sparse warnings about missing syscalls) Patch is against 5.1-rc4 (localversion-next is 20190412) arch/arm/mach-mvebu/board-v7.c | 1 + 1 file changed, 1 insertion(+)