isci: Fix infinite loop in while loop

Commit Message

Colin King April 20, 2018, 9:03 a.m. UTC

From: Colin Ian King <[e-mail]>

In the case when the phy_mask is bitwise anded with the
phy_index bit is zero the continue statement currently jumps
to the next iteration of the while loop and phy_index is
never actually incremented, potentially causing an infinite
loop if phy_index is less than SCI_MAX_PHS. Fix this by
jumping to the increment of phy_index.

[ The goto is used to save one more level of nesting that
makes the code far wider than 80 columns. ]

Fixes: 80aebef7c112 ("[SCSI] isci: Fix a infinite loop.")

Signed-off-by: Colin Ian King <[e-mail]>
---
 drivers/scsi/isci/port_config.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

James Bottomley April 20, 2018, 9:45 a.m. UTC | #1

On Fri, 2018-04-20 at 10:03 +0100, Colin King wrote:
> From: Colin Ian King <[e-mail]>
> 
> In the case when the phy_mask is bitwise anded with the
> phy_index bit is zero the continue statement currently jumps
> to the next iteration of the while loop and phy_index is
> never actually incremented, potentially causing an infinite
> loop if phy_index is less than SCI_MAX_PHS. Fix this by
> jumping to the increment of phy_index.
> 
> [ The goto is used to save one more level of nesting that
> makes the code far wider than 80 columns. ]

what's wrong with replacing the while() with a for() that just works
(removing the increment at the end).  This is effectively open coding a
for loop anyway, which is a pattern we wouldn't want replicated.

James

Colin King April 20, 2018, 9:57 a.m. UTC | #2

On 20/04/18 10:45, James Bottomley wrote:
> On Fri, 2018-04-20 at 10:03 +0100, Colin King wrote:
>> From: Colin Ian King <[e-mail]>
>>
>> In the case when the phy_mask is bitwise anded with the
>> phy_index bit is zero the continue statement currently jumps
>> to the next iteration of the while loop and phy_index is
>> never actually incremented, potentially causing an infinite
>> loop if phy_index is less than SCI_MAX_PHS. Fix this by
>> jumping to the increment of phy_index.
>>
>> [ The goto is used to save one more level of nesting that
>> makes the code far wider than 80 columns. ]
> 
> what's wrong with replacing the while() with a for() that just works
> (removing the increment at the end).  This is effectively open coding a
> for loop anyway, which is a pattern we wouldn't want replicated.
> 
> James
> 
Good point, V2 en-route.

Patch

diff --git a/drivers/scsi/isci/port_config.c b/drivers/scsi/isci/port_config.c
index edb7be786c65..55dc7c1dbc2b 100644
--- a/drivers/scsi/isci/port_config.c
+++ b/drivers/scsi/isci/port_config.c
@@ -293,7 +293,7 @@  sci_mpc_agent_validate_phy_configuration(struct isci_host *ihost,
 		 *       This is expected and required to add the phy to the port. */
 		while (phy_index < SCI_MAX_PHYS) {
 			if ((phy_mask & (1 << phy_index)) == 0)
-				continue;
+				goto next_index;
 			sci_phy_get_sas_address(&ihost->phys[phy_index],
 						     &phy_assigned_address);
 
@@ -311,6 +311,7 @@  sci_mpc_agent_validate_phy_configuration(struct isci_host *ihost,
 					      &ihost->phys[phy_index]);
 
 			assigned_phy_mask |= (1 << phy_index);
+next_index:
 			phy_index++;
 		}